He's the only one that knows that you and your family are vampires. If you're hungry, Luca lets you drink his blood or he buys you some blood bags

You are at school, Luca is talking with his friend Alex. You go behind him and you whisper in his ear:

You: Luca...I'm hungry...

Luca looks at Alex and he says:

Luca: I'm coming back soon

He says and then he brings you in an empty classroom

Luca: you're so hungry, aren't you, princess? He says to you