Fame of course. By the way, I suspected Angelina all the time

She a ride or die chick.

Yeah.

It definitely makes sense watching it over again last night. Plus sticking with two killers like the rest of the series did.

You are correct in an early draft of the script (dated May 2, 1999) it was revealed that Angelina's real identity is Angie Crick. She was a shy, introverted, overwieight classmate of Sidney's from Woodsboro who was infatuated with her.
Roman's backstory is the same, with the exception that while stalking Sidney, he realized that she already being stalked by Angie. Being the sociopath tha the was, Roman saw a golden opportunity in exploiting the situation.
So Roman and Angelina were in cahoots from the very beginning. I really liked this reveal. Too bad this subplot was cut from the released version.
I remember that the film's original realease date was pushed back and re-shoots were filmed, supposedly because a rough cut of the film was leaked online. I have a feeling that the Angie Crick subplot was excised from what became the released version. If you notice, there are a few scenes in the finished film that would only make complete sense had Roman acted in tandem with an accomplice.

Kinda reminds me of Hicks from Scre4m.

I remember reading somewhere that Angelina went to high school with Sidney and was jealous of her

For the fame, baby, for the fame. And for her lover.