@Da_Gut@poloniousmonk@bookstodon
I don't know if it's my favorite, but I read The Green Futures of Tycho as a kid and it was probably the first book that made me consider "change the future" time travel stories might actually be kind of a horror genre. William Sleator's stuff tended to be a mildly unsettling for the tween audience it seemed aimed at. https://en.m.wikipedia.org/wiki/The_Green_Futures_of_Tycho