Useless

Nico di Angelo was eight when his mother died. His older sister, Bianca, was Twelve. Shortly after Maria's death, Hades put both Bianca and Nico into an Orphanage. The orphanage was Wool's Orphanage, and there Nico met Tom Riddle.
A short Harry Potter/Percy Jackson crossover, going into a bit more depth about Nico di Angelo's childhood, and the reason Tom Riddle believes friendship is useless. Sort of One-shotish, head-canonish.