spearhedge soulmate AU? Any configuration of marks/effects?
Ooh. Okay. This is- already pretty well-trodden territory, which- fair, it's a popular fandom trope, so...hm. I sort of want to play around a bit here with the fact that Dunk- doesn't actually introduce himself in the scene where he asks Baelor to vouch for him, but Baelor knows his name later on. And the fact that Dunk first introduces himself to Plummer the steward as 'Dunk'. This one, uh- got a bit out of hand on me. But hey, the thing said five or more headcanons, right?
So, the thing is, finding one's soulmate is uncommon in general, and rarer for the smallfolk, who don't travel as much as the nobility and who aren't generally literate. That said, most people at least try to learn what the name is, just on the off chance. This has led to a few social changes in Westeros. Not extending so far as general literacy, but there's an expectation that septons, at least, will be literate. As servants of the gods, having forsaken the chance at their own bonds to serve the Seven, they are considered the most trustworthy people to read others their own marks, and as such most smallfolk learn their soulmates' names from whichever wandering septon comes through their village most regularly. According to the Faith, one can marry before one meets one's soulmate, but if either party meets their soulmate, the marriage is then considered dissolved, and it is expected that the newly-discovered soulmates will wed...regardless of their opinions on the matter. (Given that soulmate bonds can be and often are platonic, this sometimes leads to disastrous results, where two people who would have made wonderful lifelong friends end up absolutely miserable when forced into marriage.)
In Flea Bottom, we know that septons will occasionally offer charity there (Davos, two centuries later, remembers occasionally being fed by them, and I doubt that's a recent development), so Dunk learned his soulmate's name from them as a child. 'Baelor' was- an odd name to get, but he never really connected it with the heir to the throne, because- literally why would he? Baelor the Blessed was popular enough from the smallfolk to get a lot of people's kids named after him (even if most of the smallfolk ones go by 'Bael'), and among the nobility, Baelor Breakspear is notable enough to have a fair few namesakes too, even if they are just trying to court royal favour. It's a bit fancy, so probably whoever his soulmate is isn't just another gutter rat like Dunk, but whether that means 'decently off merchant family', 'devout smallholding farmers who wanted to name their kid after a famously saintly king' or 'actual nobleman' is an open question, and- if Dunk had to place his bets, it would be on option b.
Baelor, meanwhile, got his own mark at fourteen, around the time his grandfather died and he became heir to the throne. 'Dunk' is pretty obviously the name of a commoner. This- has the potential to not be great for Baelor politically. Particularly not when Daemon Blackfyre is claiming that he has his sister Daenerys' mark and that's a sign of his Targaryen legitimacy and also a sign that Daeron II is a terrible king defying the will of the gods and centuries of precedent by not immediately dissolving both of their marriages/betrothals to let them marry as is the law of the Seven! (Whether he actually has Daenerys' mark is an open question - it's considered modest/safer to always keep one's mark concealed unless it's being formally verified/witnessed by either a septon or someone formally witnessing that a soulmate bond exists for the sake of dissolving a marriage/betrothal. Daenerys never joined her voice to Daemon's to claim that she had his name, so it remains a great mystery to most of the Seven Kingdoms.) It also spurs Baelor to take more of an interest in the lives and conditions of the smallfolk generally, and edges him towards more reformist positions than he might have otherwise risked. Maybe he can never meet or marry this person the gods have chosen for him, but he can make their life better from a distance, and maybe that'll be enough.
Baelor still marries Jena, because it's expected, and because- look, the mark appeared when Baelor was fourteen. His soulmate would be three at the time of Baelor's marriage, so there's plenty of time for him to get an heir before it would be remotely appropriate to go looking. Valarr and Matarys are still born, the Blackfyre Rebellion happens, and then on a diplomatic visit to the North, Jena meets her own soulmate: Myriame Manderley, the widow of the late Lord Rodwell Stark. Formal witnessing happens, her and Baelor's marriage is dissolved by the will of the Seven, and Myriame and Jena live sapphically ever after, at court, so that Jena can still watch her sons grow up. (As Rodwell and Myriame had no children, there's nothing really tying her to Winterfell, and it's expected that a widow, after remarrying, will leave her previous husband's holdings.)
Baelor has- complicated feelings about this whole soulmate thing. Bringing his common-born soulmate into court would- likely just expose them to pain and ridicule. It's very common for common-born soulmates of powerful people to just get murdered rather than expose the family to political embarrassment, and while Baelor wouldn't and knows his father wouldn't, the fear of getting this person killed because some noble or other decided to clear the way for a political remarriage to one of their children haunts him, on bad nights. But- he has seen how happy a match can be. He and Jena came to be good friends and close allies, but Myriame makes her whole face light up with joy every time the other woman enters the room. His parents, whose political marriage coincides with their bond (which his namesake, Baelor the Blessed, took as a sign of divine will that the breach between the Seven Kingdoms and Dorne be mended), have the sort of personal and political partnership that is like lightning in a bottle. And then there's Maekar and Dyanna, who adored each other and made each other better, and Dyanna was one of the few people who could readily make Maekar smile. Baelor wants that, but- he's afraid, too, of what it will cost him and his soulmate both to even try for it, and it costs him a lot of sleepless nights.
Baelor doesn't hear Dunk's real name until a while after vouching for him. Specifically, the next morning, when he asks Plummer, the steward, the name of the knight from the previous day, and whether he was entered in the lists. It's an idle thought, because he wants to keep an eye out for Dunk during the jousting, just to see how well he does. He remembers Ser Arlan being a pretty solid opponent, wants to see how much of that he passed down to his squire. Or at least that's what he's telling people rather than- just- wanting to see this one completely random hedge knight again. So he asks- and Plummer remembers- oh, right. Ser Dunk. Or rather, Ser Duncan the Tall- and that's all he gets out before Baelor is having about three different kinds of bluescreen moment, because what are the odds? What are the odds that the knight from the previous day, who Baelor absolutely noticed and took a liking to almost at once, was the same person as the common-born soulmate Baelor has all but resolved to never look for for fear of getting them killed? Like- that particular decision tore at him before he met Dunk, but now he knows it might be someone he's met and already likes for his own sake, it's so much worse. Baelor is, however, pretty sure he's making the right decision here by not approaching Dunk about it. Like- the impression he got the previous day was of an earnest, decent, rather tactless young man who would get eaten alive at court no matter how endearing Baelor might've found him. And then Aerion happens.
By the time Baelor summons Dunk to Lord Ashford's solar for their little pre-trial conversation/Baelor essentially taking a turn as Dunk's defence counsel despite being one of the judges, he's been trying desperately to find an alternative way to get Dunk out of this situation, but- the best alternative they have is trial by combat, which is...chancy. Particularly if Aerion takes advantage of his right to have a champion, which would mean putting Dunk, a large and powerful but untested hedge knight, up against one of the Kingsguard, the best knights in the realm. So- Baelor brings this out last, one final alternative. What is the name on Dunk's wrist? Dunk- has to admit that it's Baelor, but- look, your grace, it's not what you think, there's any number of boys named after you across the kingdoms- at which point Baelor says that- yes, that's so. But, you see, the name on his wrist is 'Dunk'. This might just be a coincidence, there might be other people with those names...but it's a coincidence that will save Dunk's life, if so, and the chances of it being a coincidence feel pretty remote. Baelor is very careful about making clear- he doesn't have expectations here, if Dunk would rather go for trial by combat, they can do that and just not mention this situation. If they make it public, they will be expected to marry, and that will change everything about Dunk's life and put him in danger he may not be equipped to face. For Dunk, though- he's been daydreaming about finding his soulmate for literal years. Now he's found him, and it's- also the only thing standing between Dunk and losing his hand and foot. It's sort of a toss-up whether marrying the heir to the throne is more or less terrifying than being maimed, but this way...at least probably won't immediately kill him. And- also, it's Baelor. Who Dunk is- there's the existing hero-worship encouraged by Ser Arlan's stories, there's Baelor himself being attractive to Dunk, and then there's the fact that- Baelor has, consistently, at every turn, gone out of his way to help Dunk when he really didn't have to and nobody would've batted an eye if he didn't. So- the Crown Prince thing is terrifying, but what Dunk has seen of Baelor the person, he likes enough to take the risk.
Maekar is furious. He wants to believe his sons, is the thing. He wants to believe Aerion isn't a monster and Daeron wouldn't tell a lie that would get an innocent person in trouble just to weasel out of it himself. So Baelor going 'yeah, about that, uh- nope, your son publicly brutalised my soulmate, I am going to have to make an issue of that' is...both entirely unexpected and also the biggest fight the brothers have literally ever had. Because it's about a lot more than just Dunk. It's about Maekar's sons, and the things he now has to either confront about them or deny even harder, about Baelor no longer letting Maekar have his head when it comes to dealing with the problem of Aerion- it's a complete mess. It's not a permanent rift, but it's a rift that it takes the Great Spring Sickness, and Baelor reaching out to offer him the Handship, to really start to mend. Things aren't fully patched up until Dagon Greyjoy's reaving begins, when Dunk and Maekar are both active as part of the Crown's campaign against the Ironborn, and develop a certain rather grudging mutual respect.
It's Dunk who actually ends up making most of the moves towards going from 'married for the sake of saving Dunk's life' to 'actually together', mostly because Baelor is- painfully aware that the main thing he has going for him in terms of how this marriage happened is that he's not actually a fate worse than death, and is very determined not to take advantage of that. Having grown up with his grandfather's example as well as having to deal with stereotypes about Dornishmen has made Baelor rather buttoned-up about his desires, and very reluctant to actually pursue them. Dunk, on the other hand, has no such inhibitions and- well. Baelor has gone to enough trouble to keep Dunk alive, well and unmaimed that he's unlikely to change his mind over Dunk indicating that he- would at least like to find out if they can make this 'soulmates' thing work out for them. Which leaves them pretty much trying to do a courtship as a newly-married couple whom Baelor is working very hard to present as enough in love that Baelor would a) be devastated enough to never remarry if Dunk died and b) wreak terrible revenge on anyone even suspected of being part of any attempt on Dunk's life. Just to put off any attempts.
This whole marriage situation is- complicated, politically. The nobility are generally unhappy about it, but- well, you can't argue with the will of the Seven (at least not in public), and it's not actually the first time something like this has happened, although it's- probably the most high-profile. There's also a certain element of - Baelor wasn't showing any signs of remarrying before this, he already had two sons, but people were trying. Nobody has now succeeded, which makes fathers of eligible daughters very unhappy, but- on the other hand, nobody else has succeeded either, and nobody has gained a political leg up. It's also wildly popular with the smallfolk, because- listen. Listen. Dunk being a knight who remembered his vows was one thing. A knight who remembered his vows and who was then revealed to be the soulmate of the Crown Prince apparently as a direct consequence of doing so? That's folk hero/legend material, and every bard anywhere near Ashford is already working on the song about it.