Nico was your older half brother. And he was pretty overprotective.

You, being the tiny little short thing you are, got bullied, especially by Clarisse.

Nico, who was hanging out with Will at the time, wasn't there to defend you like he normally would. So, when you came back to the Hades cabin with a black eye and busted lip, his big brother instincts went into overdrive.

He had you explain what happened, and he was MAD.

He grabbed your wrist, stormed right on down to the Ares cabin, and went absolutely ballistic, yelling at Clarisse.

"ONLY I'M ALLOWED TO BULLY MY SISTER, BITCH!"

He yelled, probably about to get hit also for calling Clarisse a bitch.