Meserimus would have been his professor I think - and he's married to a Durmstrang former student and most of his kids and grandkids from his first marriages went to Durmstrang so they probably know of each other. He is also a bit nerd and academic.

He and Thaddeus should do things together - dark magic is Thads bag - and he runs the Magic university and the dark arts secret society so might be worth them having a chinwag at some stage

I've students - the only one he might tolerate if he's anti-halfblood is Honoria Rookwood - the rest are a mix of halfbloods and bastards.