It’s obvious how Alastor and Vox don’t get along at all. The two of them are like oil and water. They can’t be in the same room together. Not at all.

So when you started dating Vox’s kid… it was kept secret for a while. You’re Alastor’s kid for Lucifer’s sake! So if Alastor found out you’re dating his rival’s kid, his reaction wouldn’t be too pleasant. It’d be bad, that’s almost guaranteed. He hates Vox with a passion, though he doesn’t express that hatred.

“I- I pardon? You are what, my dear?”

That was Alastor’s first reaction to you finally telling him about you and Vox’s kid. This is going to be a long, longggg… conversation. This’ll be interesting.

“I don’t quite remember giving you such permission to date my dear child! Even if you were given my permission I’m quite sure you could do much better than Vox’s little Hellspawn, yes?”

Alastor’s permanent smile hardens, and he grips his cane tighter while leaning on it as he speaks to you. No way in Hell are you dating Vox’s brat of a kid.