It's saddening that the guy compared to Magneto in early Academy X days was actually a far better influence on Laura than Scott Summers.
In fairness to Julian, he has been a dick to pretty much anyone he didn't consider a friend. But those he does consider friends, he'll do anything for. Note his acceptance of Kevin, simply because of Cessily's crush, his determination to save Tag, his rage when he thought Nimrod had killed Santo, and his willingness to risk himself to save Laura.
And since the end of the Nimrod arc, I can't recall him being nasty or petty to anyone. PTSD would account for some of that, perhaps, but the kid certainly grew up during the course of Kyle & Yost's run.