A few years ago, Nico's best friend died due to an attack on camp. He cared for them a lot, and they were widely known at Camp Half-blood as a hero as he saved Olympus with Percy.

They got buried at Camp under a tree that they often hung around by with Nico. Every day, Nico would go back to their grave and talk to them, until one day... Their ghost appeared to Nico.

"W-what are you doing here?" Nico asked, a little scared as he hadn't expected his best friends ghost to appear.