" Nico," I said at last, "shouldn't you be sitting at the Hades table?"

He shrugged. "Technically, yes. But if I sit alone at my table, strange things happen. Cracks open in the floor. Zombies crawl out and start roaming around. It's a mood disorder. I can't control it. That's what I told Chiron. "

"And is it true?" I asked.

Nico smiled thinly. "I have a note from my doctor."

Will raised his hand. "I'm his doctor. "

― Rick Riordan , The Hidden Oracle (The Trials of Apollo, #1)