Roger says heyyy sup and probably calls her Lilith to be annoying. I'm sure he enjoyed snarking/flirting with her in school. And randomly arguing intelligent shit when he gets the urge. Probably made out with her bc that's what he does. And he has a Muggle stepdad so he'd talk about Muggle things with her. Probably is like hey wanna go get a cheeseburger all the time.