Class 1-A headcanons!!!!
Ever since they performed at the School Festival, they made it a frequent thing to play instruments and sing together. No practice or expectations or anything - if someone knows how to play a song and at least a couple more know the lyrics, they'll go for it. Sometimes everyone will join in, other times it'll just be a few performing and the rest watching. They become more comfortable performing in front of each other after practicing so much for their concert at the School Festival. They just do it for fun, but after Japan collapses, they do it more to raise their spirits and feel united.
◇ They perform 'Hero Too' together in the common room whenever they're about to go on a big mission and are a bit nervous. It reminds them of who they are, their values and what they're fighting for, and it helps to ground them and give them confidence.
2. They have video game tournaments!!!! Fighter games are their fav (e.g Super Smash Bros and the like, idk any others lol 😭) but they also love to play quiz / trivia games. Anything competitive goes (and if Katsuki is involved, the stakes go through the roof and the room becomes incredibly lively cos he brings sm energy to those kinds of tournaments).
◇ I can see Deku always rooting for Katsuki if they're not playing each other, and the latter rolling his eyes going "Well, obviously!". When the roles are reversed, Katsuki roots for Deku's opponent instead 😭 And then when the two of them play each other that's when everyone gets the most invested cos they're the biggest rivals in the class. It's rlly exciting.
◇ Also, Kiri, Mina and Kaminari teaching Ochako how to play from scratch cos they wanna include her in the fun. They teach her all the controls to all the games they play and have practice rounds with her. She's never been able to afford a video game console and so has never played any video games before, due to her previously living in poverty. No one in Class 1-A gets left behind!!!!!
3. After the Final War, they all become WAY too attached to each other. Half the nights they won't even sleep in their dorms - instead they'll all stay together in the common room and chat / watch movies till they fall asleep one by one (yes, even Katsuki). They bring their blankets and pillows from their dorms and lay them on the floor to create makeshift beds. They'll end up falling asleep on each other or cuddling.
◇ A lot of them get nightmares from the events of the Final War but also the Paranormal Liberation War - so much happened during those few months that they barely got to process all the events at the time, and now that everything has calmed down, their brains finally have space to sort through it. And it quickly becomes too much. It's all they can think about for quite a while. I'd like to think that immediately after returning to school after recovering from the Final War, they'd stay up late comforting each other to sleep.
