I just remembered this really cute Valdangelo AU I wrote about a year ago and never published. Basically Nico was a lonely ghost who befriended Leo, a boy who was able to see and talk to ghosts. I can't remember much else except the fact that it had this really sad, tragic ending because I'm a sadist. I'm definitely tackling that as my next story, though! I might transfer it to a Davekat story with Dave as the ghost, maybe? Either way, I'll write it for sure if I can find the story or the outline again!