Zagreus and Nico most definitely share a vibe. A vibe made of darkness and skulls.

"Yes, Grandmother would be...upset...if Mother didn't make sure to visit," Zagreus says, in a tone of voice that suggests that an upset Demeter is most definitely best avoided. "Also, glad to hear that Mother stopped Father from killing you! What did he want to kill you for?"

That last question is said utterly casually, almost as an afterthought. Zagreus might as well be asking about the weather.