@Dedicant Honestly I love developing my characters and watching them grow over the course of my story! Writing about how they react to different situations, other characters, how they respond to past events in their life and how those events shape who they are in the current timeline of the story - that's really what gets me attached to my characters and makes me want to write about them.
I think that's why I enjoyed writing originals so much, because I could build a character up from the ground and shape them how I wanted. In many cases, they'd end up slightly different from what I initially imagined them as, and that's beautiful in it's own way! Even when reading stories, I love seeing unique characters grow <3