#sevmione

When thinking about a fictional relationship between a former teacher and student, there are several issues that might get bundled together which I think is worth separating out. First off, an age gap will almost certainly exist, and to an extent that often is used as a clumsy shorthand for differences in life experience, naivete, and power imbalances, which are distinct issues which (as @dufferpuffer rightfully pointed out), can be issues in any relationship regardless of an age difference.

Another thing to consider in the Snamione-specific context is the topic of authority, professional boundaries, and the fact that one person was an adult and knew the other as a child... but we'll get back to that, and first consider the WW's attitudes just towards age gaps, exploring some of the issues of life experience and power in the relationships in the series which feature them.

But first...

Some General Wizarding Background

On average, wizards live longer than Muggles, and potentially can bear children for longer as well. Witches and wizards can also presumably work for more years than Muggles might, extending the amount of time that individuals of different ages would be at the same 'stage of life' or likely to meet in a casual, friendly context - sharing work friends, hobbies, etc. Even coming up on a 30+ year age gap may seem less significant if you're going to live to 150, especially the older you get.

There is also no higher education in the modern/Muggle sense, and students go into the workforce almost immediately after school finishes - at which point they have already been considered a legal adult since they were still in school at 17, free to use magic without supervision, drink, and can potentially be sent to Azkaban. Presumably in this work context they train on the job - and without putting too fine a point on it, it does make me think of the joke "never ask a PhD supervisor where he met his wife" because she was probably his former student.

I imagine, then, if wizards haven't married their school sweetheart (as the series suggests they are wont to do - see Lily and James, Molly and Arthur, Ron and Hermione, etc), they must be mingling with people of all sorts of ages in a work/life context, and that is also where the remainder of people are meeting their partners.

But, even if they have married young, some of them will later divorce. Divorce does seem to exist in the WW, though it doesn't seem to be in the books. Plus, certainly some people are widowed, and they can (and do) get remarried. This opens up the possibility that they could remarry someone at any stage of life, have children later, and age will become less and less relevant.

With that out of the way...

Confirmed Age Gaps & Attitudes Towards Them

I got to thinking about some of the confirmed relationships with what could potentially be considered an age gap in the books, and how characters around those relationships spoke about them.

Most notably, I was thinking about Remus/Tonks (13-year gap) and Fleur/Bill (7-year age gap). For the purposes of thinking about socially acceptable relationships in the WW, I won't be considering Bellatrix and Voldemort (which was about 25 years - but they were both DEs, Bellatrix was married to someone else, and Voldemort was Voldemort, so probably nobody was worrying about his private/love life so much as they were worrying about him taking over the world and killing people).

Tonks & Lupin

Tonks was around 22 or 23 when their relationship began, while Lupin was about 35 or 36. Despite that, everyone seemed pretty desperate for Tonks and Lupin to get together. I'm sure there's more nuance to it than that, but my point is that despite several fairly significant barriers including the fact that there was a war on and that Lupin was a spy and a cursed creature, an age difference of more than a decade was not treated as one of them. The only person who seems particularly bothered by the age difference is Lupin himself - and you could argue that it's just another convenient excuse and not something he passionately believes, because he's arguably more concerned about being a werewolf and the impact that has on his life than he is about their age:

“And I’ve told you a million times,” said Lupin, refusing to meet her eyes, staring at the floor, “that I am too old for you, too poor … too dangerous. …” “I’ve said all along you’re taking a ridiculous line on this, Remus,” said Mrs. Weasley over Fleur’s shoulder as she patted her on the back. “I am not being ridiculous,” said Lupin steadily. “Tonks deserves somebody young and whole.” “But she wants you,” said Mr. Weasley, with a small smile. “And after all, Remus, young and whole men do not necessarily remain so.”

Mrs Weasley has said "all along" not only that the age gap concern - and the others - were ridiculous, the "all along" hinting at the idea that this is a fairly well-established belief. But, we could even interpret that the WW (or, certainly the Weasleys) just doesn't care about age gaps very much, since - as Arthur points out - young and whole people do not remain young (and whole) for long. This sort of ties into my views from above that once you reach adulthood in the WW, once you are out of Hogwarts and working, perhaps even only for a short while, you aren't really considered adolescent, but adult yourself. No matter how young you are, sooner or later you will no longer be young, so - who cares?

There were also some quite understandable concerns about whether it was safe for Tonks to be with Lupin, and whether it was wise for them to have children, and those concerns seemed to matter far more than the age gap itself. Still, I might argue that if the age gap were that big of an issue for people more widely than just Lupin, it would've been revealed in this and similar conversations.

Life experience & power

Despite the age gap and any perceived experience or power imbalances coming from that angle, Remus was considerably less socially powerful than Tonks - as a werewolf he faced discrimination, social isolation, financial hardship, etc. Meanwhile, Tonks was very much in a position of authority - she worked for the Ministry, under a highly respected and experienced Auror (Moody), and no doubt was a talented and respected Auror herself. She had a secure income, seems well-liked, and was not subject to any discrimination that we're aware of. There's a level of social safety there which I would argue is more substantial than just her being younger - though you could argue that being with Lupin made her an "outcast" and that few people outside the Order approved of their relationship.

Still, Tonks had also been out of school for several years by this point; she had completed her Auror training and was working in what was presumably a highly demanding job, giving her a fair amount of life experience and the knowledge to expect that situation and potentially navigate it - but the same can't really be said of Fleur...

Bill and Fleur

Bill and Fleur are in a somewhat similar position to Remus and Tonks in that there is both an age gap and some potential barriers to the relationship. Fleur would have been around 17 or 18 when she first met Bill, while Bill was already in his mid-twenties. Seven years or so between them is, perhaps, not a substantial difference (and certainly wouldn't be between older adults) - though it may seem more noticeable at this stage since Fleur is still only a teen.

Whatever we might think of that in a real-world context, it is interesting that nobody in the WW seems concerned by the fact that Fleur is fresh out of school, living in a foreign country, and... dating a man who met her while she was still a 17-year-old student, competing in the Triwizard Tournament:

Fleur Delacour, Harry noticed, was eyeing Bill with great interest over her mother's shoulder. Harry could tell she had no objection whatsoever to long hair or earrings with fangs on them.

Instead, the objections to the relationship focus almost entirely on Fleur herself. Molly, Ginny, and Hermione all spend a good deal of time criticising Fleur - but the criticism is that she is vain, conceited, and not a good match for Bill. Nobody suggests that the age gap is inappropriate, or that Bill should find someone closer to his level of life experience.

Life experience & power

Returning to the idea that nobody seems concerned by the fact that Fleur is fresh out of school, living in a foreign country, and dating a man who met her while she was still a 17-year-old student, and the fact that nobody raises concerns about Fleur's relative youth or lack of life experience, or that she is a second-language speaker in England, that she only has money (presumably) from working part-time, or that the family she's marrying into doesn't like her and would, it seems, not piss on her even if she were on fire, or that the first time Bill saw her, she was still in her school uniform... the HP Wiki even says they started dating immediately, so presumably neither Fleur's parents nor the Weasleys had any issues with Fleur meeting Bill whilst Fleur was still in school, before taking a part-time job abroad to improve her English. Potentially, she also got the job to spend time with Bill - which might suggest they'd gotten quite close whilst she was still a student, because otherwise it's a heck of a coincidence that she finished in school in the summer of ~1995 (according to the Wiki?), got a job in the exact same place as Bill, dated him for a year, and was already set to marry him by September of 1996. What we find out later is that they go to live in a house that used to belong to the Weasleys' aunt - possibly also suggesting that Fleur does not have the means to get her own place, but what do I know? She could have family money, even if her part-time job didn't bring in enough for a house.

Anyway, contrast this with Bill: from all we hear about him, he "likes a bit of adventure, a bit of glamour", is widely liked, and seems successful - and after graduating from Hogwarts he went to work for Gringotts Wizarding Bank as a cursebreaker, so has a secure job which has given him plenty of life experience for the last 7+ years. He also has a large family in England who hate his girlfriend/fiancee and who would 100% take his side on just about anything. Personally, I think that's a little scary. Imagine if he wasn't a nice guy, and Fleur needed someone to turn to.

I think what Bill and Fleur show that Tonks and Remus do not is that the WW are unconcerned by age gaps, even when one individual is still young, somewhat isolated, and relatively inexperienced - eyeing her future husband whilst wearing her school uniform, even.

You could, on the flip side, also argue that Fleur - despite her age, being away from home, the language barrier, being disliked by her fiance's family, only having part-time work, etc, was also smart and magically powerful enough to compete in the Triwizard Tournament, and had a family who very likely supported her both financially and emotionally. She is also part Veela, and could exert a level of influence over (straight?) men in particular, even in groups - however, this would not protect her from or help her convince other women to help her, should she need it.

Which led me to another, tangentially related area of thought...

Interspecies Relationships

The WW also appears to be relatively accepting of (at least some) interspecies relationships, depending on the other species involved. There is certainly prejudice against some groups; Hagrid's being part-giant is treated as scandalous by the likes of Rita Skeeter and the Malfoys, but he is ultimately able to keep his job and friendships even once that is known, and Flitwick supposedly has goblin ancestry, though I honestly can't remember if this was touched on in the books at all. Fleur being part-Veela makes very little waves. I won't even touch on the part-house-elves. It's clear that goblins can consent, probably so can Veelas from what we can see (and perhaps the concern ought to be whether or not the humans can consent properly, given the powers of the Veela). However, giants are a whole can of worms I'm not sure I want to get into, since they are generally described as less intelligent than humans and any relationship with one would have, uh, implications in terms of consent, and house elves - I begrudgingly add - were rarely free, which has its own host of messy implications for being... with them.

In any case, nobody in the books seems particularly concerned by inter-species relationships. If Hagrid being part-giant was considered so bad by more than just the likes of the Malfoys, or if Flitwick being part-goblin was widely known and considered poorly, we'd see more parents writing to the school about it - like Remus expected the parents to do when they found out he was a werewolf.

So, what other relationship norms do we have to compare?

Consanguinity

Well, another key thing to consider from this perspective vs our own is consanguinity - aka "the close union, sexual relationship, or marriage between individuals who share common biological ancestors". This is, obviously, not a big deal at all in the wizarding world, though it is sometimes (depending on the relation) considered taboo irl.

However, we hear from multiple characters that all of the Pureblood families in England are essentially related, and the only question - if it is asked at all - seems to be how closely. The Gaunts and some other families were sometimes judged as unstable or violent "due to their habit of marrying their own cousins", so there seems to have been no law preventing first-cousin marriage, and I have to wonder just how many cousins you can marry down the generations before the family tree starts looking more like a family bush.

But, to hardly even paraphrase a comment I made below, Pureblood families seem to have no stigma attached to marrying someone they 100% know is related to them in some way - but neither does anyone else, really. Even though it turned out not to be true, even Harry/Ron/Hermione didn't seem all that surprised that Tonks might have been in love with Sirius, and they were cousins (once removed? twice? his niece? idk) - so maybe the whole WW is just pretty laid back about it - which is perhaps to be expected, especially with such a small population (both in terms of the Purebloods specifically, and the magical population of Britain more widely, and where marrying a Muggle isn't exactly encouraged, and the only alternative is to marry another species or a Muggle-born, apparently).

So, I don't think the WW would care about or prevent anyone's relationship, especially when it is between two consenting adults - and I think this is also true when considering it not only from the angle of the age gap itself, but also from other angles which we, as modern readers, might question.

But for ships like Snamione (and others like Snarry), I have to wonder whether they'd have any issues with former student-teacher relationships specifically. So, we move on to part two: teacher authority, professional boundaries, and the fact that one person was an adult and knew the other as a child.

Power Imbalances and Professional Boundaries For Teachers

Similar to some of the points I made above, and very much the sort of thing that antis like to latch on to, is the fact that Snape was once Hermione's teacher. He's known her from the age of eleven, in a position of authority, and the concern in real life would be how much that might influence the beginning or the dynamics of their relationship.

But, in the wizarding world would this be such a barrier? There are already pretty weak student-teacher boundaries within Hogwarts, ones which just about everyone is aware of.

Hagrid

At the age of 11, Harry, Ron, and Hermione befriend Hagrid, a fifty-year-old man. They go to his house unsupervised fairly often for tea and cake, and sometimes even visit/sneak in after curfew; they have helped fix him up when he's drunk; and they have carried out his dirty work (Norbert, Grawp) - and nobody seems to think that this is especially odd. This isn't to say that you can't be friends with someone of a substantially different age - I certainly have friends significantly older than me, and have all my life - but that in some modern/Muggle contexts it might be considered unusual, especially since Hagrid is a member of staff at their school. Babysitting a member of staff when they're drunk might be one of those times it could be considered unusual (and, if we look to the other teachers, accompanying your headmaster to a cursed cave only to watch him drink poison and fight reanimated dead bodies is probably touching on some safeguarding issues, as well - but then Dumbledore's whole thing about raising Harry to die is just like. its own thing. but the point stands).

Lupin

We could even use Lupin as another example - he befriends Harry to an extent in PoA, with Harry taking extra lessons not central to his schooling, ending up staying for a cup of tea on occasion, and they remain sort-of friends outside of school (certainly they are acquaintances - enough that Harry feels confident to vocally judge Lupin's choice to abandon his family). There is never any suggestion from the other students or adults that this is unusual in any way, either when they are in school or after, just because he was once Harry's teacher. The fact isn't even brought up when Lupin slams Harry against a wall. Even though Harry is still of school age, and they have referenced Lupin having been their teacher in that very conversation, in that context - both as near-adults or adults, both effectively part of the resistance - they were considered practically peers, on a first-name basis, with Hermione asking about Lupin's relationship and Lupin inviting himself along for the ride (aka the Horcrux hunt) before throwing Harry against a wall and then leaving.

Hogwarts in general

Sort of similarly, nobody is apparently overly concerned if the teachers get drunk in front of the students, which we can see at a few events like the Yule Ball, a Christmas or two, Trelawney walking around smelling like sherry, and Slughorn's parties. On a similar note to the drunken teachers above, nobody even seems to care if the students are getting drunk with the teachers, since Slughorn was drunk at a party with the students, at which they had access to alcohol at around the age of 15 or 16. If Slughorn was the host (and presumably the one in charge), then the students were free to indulge however they saw fit. I know attitudes towards alcohol in the UK have always been pretty relaxed compared to, say, America - but even when I was caught underage drinking at the age of 17 on a school trip in sixth form, I still got in plenty of trouble for it, because it was a school and they had laws to follow and the teachers were in a position of authority to look after us :P

In fact, you could argue that Hogwarts, its teachers, and its governors - and presumably parents outside - don't care much for student welfare at all, because outside preventing (in most cases) physical punishment, Hogwarts has a very relaxed attitude towards their safety. As @severusshouldsue points out in the comments:

Harry is literally intended to be a human sacrifice at one point, the only people who are really against that are Molly Weasley and Severus Snape. And i'd argue they aren't even opposed to child sacrifice as a concept, they just feel strongly about it because they're personally invested, with Molly feeling like a mother to him and Severus having dedicated his entire adult life to protecting him.

...and:

Throughout the books we see teachers sending small children into the forbidden forest as punishment, leaving children under the supervision of unsafe adults like Gilderoy Lockhart, and in the case of Dumbledore and the trio, even grooming them to be child soldiers. So while teacher-student relationships are of course unethical and unsafe, it's hardly worse than a teacher having an eleven year old face a mass murderer alone. Of course nobody is going to care about safeguarding in a world where children are essentially handed weapons at the age of eleven and left unsupervised with them. We cannot compare it to our world where eleven year olds require supervisision to use a bunsen burner.

...which are some excellent points well made.

Slughorn

Slughorn is a particularly interesting example here. Now, I didn't go to a boarding school, so maybe some of this is pretty normal when you're living in the same place as your teachers, idk - but nobody seems concerned either that Slughorn was, across his whole career, befriending and using students for favours from potentially the age of about 15 or 16, both in and outside school hours. Nobody mentions that it's odd that he has private dinners with them. Nobody thinks it is strange when he brings vampires, who are looking rather thirsty, to the party to ogle the students. Nobody minds that he continues to spend time with his ex-students outside of school once they become adults, having formed a sort of friendship with them whilst all of them were underage. Presumably, some parents and relations of the kids in school at Harry's time were still friends with Slughorn - and it's not a leap to imagine that they wanted their kids in that club, too, and even encouraged it.

Molly does seem to suggest that he's perhaps an unusual man - but her issue seems to stem from the fact that Arthur was not especially highly regarded by Slughorn, rather than the fact that Slughorn had a social club to recruit students for favours at all:

Of course he can be charming when he wants to be, but Arthur’s never liked him much. The Ministry’s littered with Slughorn’s old favorites, he was always good at giving leg ups, but he never had much time for Arthur — didn’t seem to think he was enough of a highflier.

But again, I'm not really commenting on how odd these behaviours are or are not, or saying anything about the possibility or appropriateness of friendships and relationships between people of different ages who may or may not have once held positions of authority over one another - I only bring it up to make the point that the wizarding world just doesn't seem to care. Much like its attitudes to love potions, school safeguarding, and corporeal punishment, the WW sometimes has a rather laissez-faire attitude to things we would consider a Big Deal in the real world.

Teacher relationships

Through desire, circumstance, or plot convenience, most teachers at Hogwarts do not seem to date, have any romantic relationships, significant others, children, etc, at the time they are teaching - but that doesn't mean they can't. In fact, if I have to know this then so do you: apparently Flitwick and Sprout dated for a while, so teachers are permitted to date each other, and they have:

And if we care to use the above example (and I have no idea whether I do, but thought I'd work it out for fun anyway), then Flitwick was born in or before 1958 according to his wiki, meanwhile Sprout was born in or before 1895, giving them a 27-year age gap. I have no desire to research this properly, and no knowledge about whether or not there's any hard evidence, but potentially Sprout could've taught Flitwick, I guess. Regardless, by that point, they were both peers in basically every sense - as would Hermione and Snape be, in aus where they are both teachers.

Returning to Snape and Snamione specifically (and similar student/teacher ships) for a moment, I also think that the WW wouldn't care for another reason: it would be inconvenient to enforce, or even care much about, a rule that teachers cannot date former students. If teachers were permanently barred from relationships with anyone they had taught, then in Snape's case that would effectively cut him off from getting involved with almost anyone younger than himself by more than a few years, because when he started teaching he was perhaps 20, and his oldest students would've been 17 or 18. Hogwarts educates practically the entire magical population of Britain:

"nearly every witch and wizard in Britain has been educated at Hogwarts, but their parents had the right to teach them at home or send them abroad if they preferred"

...and many witches and wizards spend their lives interacting with the same relatively small group of people. It would be difficult to maintain as strict relationship boundaries in a society structured that way, and even harder for a teacher like Snape, who taught practically everyone younger than him by more than a year.

Given what we know about the rather loosey goosey boundaries that already exist between teachers and students, I struggle to imagine many people caring once the student in question was considered legally an adult.

Looking at Slughorn in particular, who openly cultivated some pretty close relationships with students and continued them long after graduation, I'm not even convinced it would automatically cause outrage if the relationship began while one party was still at school - though that is, obviously, moving into somewhat more speculative territory.

With all of that in mind, what sort of relationships are frowned upon in the WW, and how might that influence Snamione?

Taboos

Love potions

Although love potions are treated fairly flippantly throughout the series, certainly Dumbledore is quite judgemental about Merope's use of a love potion on Tom Riddle Sr. in order to marry and conceive, so presumably there's some judgement there, and they are supposedly banned at Hogwarts - though, apparently, not enough to prevent them being taught there. They're sold in joke shops later in the series and I'm also fairly sure (but don't take my word for it) that Molly makes a joke/fondly reminisces about the time she used one (on Arthur?), though I think it must have been fairly weak.

Werewolves

Given the earlier sections of this meta, it would be remiss of me not to mention Lupin. Outside of the Order, plenty of people have an issue with Tonks and Remus being in a relationship:

“You have only ever seen me amongst the Order, or under Dumbledore’s protection at Hogwarts! You don’t know how most of the Wizarding world sees creatures like me! When they know of my affliction, they can barely talk to me! Don’t you see what I’ve done? Even her own family is disgusted by our marriage, what parents want their only daughter to marry a werewolf? And the child — the child — ”

...but that is arguably because of the (valid) fear people have of a condition which turns someone from a perfectly reasonable human to a cursed creature whose goal is to attack humans, and the perceived risk of Tonks being infected - not at all helped by the fact that werewolves like Fenrir were out there attacking people at all times of the month, and compounded by the unknown factor of whether or not the baby would turn into a werewolf itself. So, being a deadly cursed creature is considered taboo.

Blood purity

Fairly self-explanatory; in Pureblood circles, it's shunned to marry those of 'lesser' blood status, be it Muggle-born or sometimes even half-blood, but it wouldn't be that remarkable outside of those circles. But given the fact that most wizards don't know the first thing about Muggles, how they speak about Muggles as less-than, how they treat Filch, and that even the Weasleys "never talk about" their Squib relatives, I think it's fair to say that most wizards might look down on a marriage with someone without any magical ability at all (Muggles and Squibs), whether they were open about it or not.

I think you could - given the general nature of the WW - reasonably extrapolate that the same rules apply to elements like social class and wealth, though these are obviously intertwined with magical heritage and blood purity, though I can't remember relationships of that nature being touched on in the books.

There was a really great meta or ask response somewhere about Snamione and the challenges they might face in a relationship (that Hermione is comfortably wealthy or (upper-)middle-class since she goes skiing, both parents seem to have well-paid jobs, etc, vs Snape having grown up neglected and quite cripplingly poor, and the differences in worldview that could provoke), which I think could also tie into this section in fics, but often doesn't imo. If I remember where I found the meta/ask, I'll link it here, and if anyone knows the one I mean, please do send it to me.

Anyway, I don't think the general WW would care - a Muggle-born and a poor half-blood with a Muggle name wouldn't make (m)any waves unless it was at the judgement of Purebloods - but I'd like to see more of that in fics.

In conclusion...

None of this is written with the intention of passing a value judgement on age gaps, power dynamics, or how these relationships are portrayed in real life or in HP. Like I say, I think it's interesting to consider how differently the WW appears to view certain issues compared to readers, and it's also been fun systematically debunking a belief of mine that's been bugging me as I read Snamione fics (unnecessarily, apparently).

Much like love potions and teacher behaviour at Hogwarts, which many readers find uncomfortable and weird in concept but which are often treated mostly as a joke within the books themselves, age gaps and former teacher-student relationships maybe wouldn't provoke the same response in the wizarding world that they do in the real world. Based on what we actually see, if Hermione - or Harry, or another former student - ended up dating Snape (especially several years after leaving Hogwarts), I suspect the reaction would be more focused on Snape's personality and history than the relationship itself. People might object because he was a former Death Eater, because he killed Dumbledore, because they didn't trust him still - or just because they didn't like him or thought he was ugly or unpleasant. It would pay to have Rita Skeeter on side - she tends to write whatever she thinks will sell, and sways lots of attitudes with it. A semi-decent PR campaign would basically convince the entire WW that it was a love story for the ages.