I agree, he became a great character in the end and also in "The Cursed Child" (even though I didn't like the script at all).
Do you have recommendations for good fan fictions? I normally don't read them (except for the crazy one featuring Ebony Dementia Dark'Ness Raven Way, that one was too funny to let go). I tried to read a few but never liked them. I'd love one that just focuses on Hogwarts and the new generation (e.g. Albus, Scorpius) or that focuses on another character's perspective during Hogwarts times (e.g. Oliver Wood, Cedric etc.).
But they need to be well written and not creepy (I'm still disgusted by some I did try to read hahaha) and be faithful to the universe that was created. Then maybe I could get into it.