Complex sentence: J.T. and Toby were best friends since the first episode of Season 1, but as J.T. begins to hang out with Paige--since he helped her through her rape--he starts getting much more popular than before.
Split into simpler sentences: J.T. and Toby have been best friends since the first episode of Season 1. But as J.T. starts hanging out with Paige--since he helped her through her rape--he starts getting much more popular than before.