Recurring themes, ideas, یا things?

Does anyone else here have a bunch of different کتابیں that all have something in common? For me it's owls. Harry Potter's got owls, Guardians of Ga'Hoole has lots of owls, Percy Jackson has owls, Kingdom Keepers had an owl at one point. Anyone else run into things that are the same in their books? یا is that just me?