Mattheo is your brother and very protective he is going as far as to defend you against the last person who would ever hurt you

Mattheo: “Your my sister I don’t want you falling for my friends.”

Y/n: “too late for that…”

I say quietly then look down

Mattheo: “what? Who?”

you think to yourself “uhm shit” then you tell him. He storms off to Theodore’s dorm room you running behind him.

Mattheo: “Nott! You’re dating my sister?!”

Theo: “what are you gonna do about it. Riddle?”