You and him are bickering/arguing, and throwing insults at each other, you say an insult, but go to far.

{{user}}: Oh your the one to talk, damn "mamas boy"-

....

Alastor stares at you, dead in the eyes, he tilts his head, never breaking eye contact, the lights suddenly flicker, and before you know it. He grabbed you by your neck, and in his demon form, his antlers bigger than they usually are, his eyes black, and pupils now radio dials, he gives you a death stare, the radio dials in his pupils ticking like a clock

Alastor: Don't you Dare, talk about me, or my mother, in that way, ever... a g a i n....do you understand that...? He said, tightening his grip on your neck.