Yay, a new fandom means new headcanons, and what better way to spread the love than making another headcanons fic! Someone please come and scream at me to write KAiA, JFC. I'll only be doing the characters that I've seen so far in the anime, (stupid me hasn't read the manga), but if you want a particular character added, just let me know.
As always, I do not own Shingeki no Kyojin, or any of the characters.
Eren tends to take up the whole bed, spreading out in every direction, regardless of anyone else. Trying to move him will usually result with a kick to the face and an angry grumble.
Armin in contrast tries to take up as little space as possible by curling up into a tiny ball, and will apologise profusely if he disturbs anyone.
Mikasa sleeps on her back, arms folded over her stomach, and sometimes looks almost dead. She also sleeps very deeply, which is a terrifying combination for anyone not used to it.
Bertholdt hugs a pillow in his sleep, wrapping his arms and legs around it, and drooling messily. If there's no spare pillow, he'll settle for the nearest person.
Reiner spends most nights trying not to be hugged to death by Bertholdt. This almost always fails, and he spends his nights hoping that he wakes up first so no-one sees.
Sasha drools more than everyone else put together, thanks to her constant dreams of food. She can often be heard sleep-talking about various delicious meals.
Connie sleeps upside down, with his feet on the pillow and his head at the other end. Comfortable for him, not so much for anyone who ends up sleeping with his feet in their face.
Marco sleeps sideways. Not sideways as in 'on his side', sideways as in 'my head will be near one person, and my feet near another'.
Jean is made to put up with Marco's feet. That's why he sleeps with his head under a pillow, and small bits of cloth stuffed up his nose.
Ymir and Christa tend to sleep back to back, to avoid getting kicked in the back by anyone else. It's also useful in winter, since they share body heat like that.
Annie sleeps as far away from everyone else as possible. Partly out of choice, and partly because she practices fighting moves in her sleep.
Levi wraps himself up like a blanket burrito. It's like his night-time stronghold against dirt and the cold.
Hanji rolls around a lot, flinging her arms in various directions, and shouting loud and uncomfortable scientific facts every hour. ((Who wants a separate chapter for that?))
Erwin lies on his front, face buried in his pillow, and wakes up several times in the night due to not being able to breathe properly.
Mike preferred to sleep curled up in a nest of pillows, until the pillows got confiscated after he used them as missiles. Now he has ONE pillow.
Petra sleeps wherever Auruo isn't.
Auruo doesn't get much sleep. He stays up late improving his Levi impersonation.
I think that's all of them! And yes, I'm including Marco; don't try and stop me! As per usual, your own headcanons are welcomed, and the next chapter up will either be 'Drunk' or 'Mornings'. CYA, bros!