Hey there, anon! Tbqh, frouis is probably our happiest, fluffiest ship, so there’s not a lot of angst to be had from us, if that’s what you’re looking for. This is about the best we’ve got:
If one of them died, they’d keep (and probably wear) an article of their deceased love’s clothing - Francis would keep Louis’ tie, and Louis would keep Francis’ vest. They’d also probably get quieter and more serious. Being separated would be very upsetting for them, too.
Also (and this ends up being too cute to be angsty, sorryyyyyy):
Louis might have times when the fact that nothing will ever be the way it was before the outbreak really hits him, and he gets kind of bummed out, and Francis would try to be positive and cheer him up in the most Francis-y way possible like “Hey, we can live in any house we want now, and no one will call the cops or make us pay taxes!” (Francis has probably never payed taxes, he is a degenerate)
Louis definitely appreciates this, and jokes that maybe he should try to be more like Francis, then procedes to gently throw a can of beans at the wall. “I hate beans?” Francis is very proud, until Louis goes and picks up the beans (and apologizes to them) and puts them back where they were because they need to take stock of their food supply, what a nerd.
After this, Francis probably tries to get Louis to talk about the things he hates, but all he can come up with are zombies (“Come on, man, even zombies hate zombies. Be more creative.”), getting gum on your shoe (“Yeah, okay, I hate that, too.”), and how Gary from Accounting used to steal his stapler (“Fuck Gary. He’s probably a zombie now. And not even a cool one. He’s, like…a jockey or something.”). Louis still gets a rush out of it, though.
I’m so sorry, anon. We tried to come up with more feels-inducing headcanons, but it always ended up getting cute, idek. It was emotional in a positive way?? If we come up with anything else, we’ll post em here!