i'm a sucker for the sentient nrc dorms theory, so have a few situations (featuring inspirations from a conversation with @riddle-peakhearts)
heartslabyul tripping a student on the stairs while they're skipping chores and riddle is after them
savanaclaw blowing sand/dirt into someone's (read: lilia's) eyes
pomefiore using a gentle breeze to fix someone's hair or clothes
ignihyde fixing a game-breaking glitch in someone's game
diasomnia playing chess with its students
octavinelle subtly moving something that would've tripped a lounge waiter with a heavy tray
scarabia subtly pointing a student towards the right direction in the textbook they're using
but also more... uncanny things
the lights in ignihyde slowly pulsing, like a heartbeat, or breathing
random howls or roars in savanaclaw despite none of its students making such noises at the moment
the rose maze in heartslabyul rearranging itself, leading countless students to get lost despite swearing that they know the layout
mirrors in pomefiore sometimes reflecting movement that those beholding them never made, or momentarily reflecting people that aren't present at all
music echoing through the halls of scarabia with no true source
human, and only human, students of octavinelle swearing that they hear singing coming from outside
random alluring lights and humming in diasomnia, tempting students to the high spires of the dorm or the depths of the basement
ace and sebek's brothers always answer their confused calls with long stories of their own from their time at nrc. the teachers affirm the oddity of it all. but after a few months of adjusting, nobody really questions it. housewardens will warn their freshman of what and where to avoid, will teach their successor about the ins and outs of the dorm and its behavior, but it's never really properly addressed and barely ever acknowledged. some dorms (read: heartslabyul) are more obvious than others, but all of them have a degree of life that some students find incredibly discomforting.