My favourite headcanons about Davekat
Size difference- but it goes both ways! Dave is taller than Karkat until thry turn 21 or so and Karkat's moult permanently makes Dave the small one. Not that he's complaining
Codependence. These two are a menace to friends and now they are are a menace to anyone trying to speak at all. Good luck finding one of them alone, Karkat is just around the corner and you interrupted Dave finding him. Dave has taken to wearing Karkat's clothes and now you don't know if he owns any clothes in his size at all.
Jealous Dave and Insecure Karkat. who is he spending time with that is not me vs the people he's spending time with will replace me.
No kids. Babies are cute but I think they have too much shit to work through before having their own. Very good uncles though
Some honourable mentions
Karkat as waifu
Dave knowing anything about sports or being popular
Body swaps (because nothing says getting to know you better than chilling in their body and dealing with your aches and pains)
Immortality issues















