since kateaaron has been on my mind lately, here's how i think their relationship goes:
firstly i headcanon kate as someone who has a single parent and 2 siblings, but she had a pretty regular life all in all
also she has a protective streak which i have a backstory idea for but i need to hash it out more
she also is a good people reader i feel like
anyways that's not really important to how kate and aaron got togheter but it gives more of an idea to how i see katelyn and how it might influence her relationships
they firstly met in class but i don't think they noticed eachother right away
katelyn noticed him first because of the rumours going around about andrew and by extension aaron and i think at first she was really curious
i think aaron noticed kate when he saw her at one of the games and realised he had seen her in most of his classes (he probably thought she was cool and just that)
i think kate made the first move (she was really curious about aaron and wanted to know more about him, since at that point he was this mysterious but smart and sweet guy) (she thought he was sweet because he never bothered anybody and the few times they interacted before he wasn't anything but nice if closed off)
she probably sat next to him in one of the classes and continued doing so since she found out she liked his presence even if he barely talked (unless it was to say shit about the teacher)
at first aaron was confused bc why was this nice cool girl always sitting next to him like she could find better company (in his mind)
but anyways they started really talking, sharing things about themselves or stories from their childhood (aaron avoided talking about tilda for a while)
they become close pretty quickly and started hanging out outside of classes (which aaron framed as study club to the monsters which sometimes it kind of was)
sometimes kate's friends joined them (marissa, alex and him bonded once they found out they're all skaters while sean and pen didn't like that he was closed off but they didn't really have a problem with him at that point)
but anyways they just kept going on these little dates (they didn't call them dates but it was basically what it was) and they only grew closer and closer
aaron started sharing bits about how tilda was (kate decided then and there she hates that woman) and also about his relationship with andrew (kate had mixed feelings about him and she still does but she can understand and respect his desire to protect aaron in any way he could)
i think their relationship consolidated somewhere during the summer that neil joined the foxes
kate realised she loved (liked felt too small of a word) aaron during a conversation with marissa where she pointed out that whenever she has a chance to hang out with aaron she just drops any previous activity and goes to see him (she even bailed on her friends once or twice or more and that's what mari was complaining about)
anyways katelyn apologised and then said to marissa 'i love him' (and it didn't feel like a big revelation, just something that was always there, waiting to be named)
marissa wasn't even shocked she used the word love
as for aaron he had figured out his feelings for a while but was scared to act upon them because of the deal he had with andrew and he didn't want to lose kate
katelyn debates confessing for a while until she just decides to fuck it and do it (she knew that aaron wouldn't be the type to avoid her even if he rejected her and if she could still have him in her life all would be ok)
but once she confesses to him, aaron just breaks down, explaining the deal to her and how he knows andrew will come after her if he finds out
and i think kate'd say something like i'm not afraid of your brother (she kinda is but aaron is worth to her more than anything andrew could do to her)
and then aaron drops the 'he killed my mother' (and kate barely holds back saying that that makes her like andrew and just says 'i won't give him a reason to do that to me then')
the start of them dating is pretty rocky since aaron is still kind of afraid even though katelyn always assures him she can take whatever andrew might have in store for her, but she accepts to keep it secret for now even tho she's the type to flaunt relationships (especially when she never loved someone like she loves aaron) (when pen and sean are informed of this they say 'he's not worth it girl') (they don't know how much he's worth it to katelyn)
but with time aaron gets comfortable in their relationship and starts making plans to tell andrew (he never goes through with them)
meanwhile thanksgiving happens and kate gets a phonecall in the middle of the night ('he was hurting andrew and i-i killed him kate i killed him. he's dead and i- it was so easy kate so easy to kill him') (kate doesn't know the full story until much later)
(later aaron tells her he doesn't regret it, he might feel guilty for killing a man but he'd do it all over again if it meant protecting andrew) (she holds him the entire time and aaron vows to never let her go) (katelyn doesn't get how anyone can hate him)
and then aaron clocks neil and andrew and a plan forms but he doesn't know how to go around saying he knows about them (so he still holds it off) (when he tells kate of his half-baked plan to use neil she just laughs bc it's really ridiculous that it's the most likely to work plan) (aaron starts laughing too)
but while aaron is preparing his scheme neil shoves his nose into his bussines and kate accepts his propsal (she saw how much the distance between him and andrew was hurting aaron and if it got andrew off their backs in the meanwhile even better)
pen and sean want to throw a congratulatory party thinking they're breaking up for real but even they realise something more is going on
the twins go to therapy and kate and aaron are back happily togheter
aaron manages to bring the neil topic in conversation a few times but andrew always denies his importance
then baltimore happens and andrew can't deny it anymore (the deal is broken) (the cat was out of the bag anyways)
andrew goes after kate and she strengthens her resolve to never give him a reason to do that again (or worse) (she was scared but giving up aaron never even crossed her mind)
and kateaaron get to live their best lives and grow old togheter (they can't imagine it any other way)
(everyone thinks they're cute togheter, even sean and pen (and andrew))