Probably wrong theory about Vinny, Quinn and the shit that's going down.
Quinn shows up at B&R as a reject and pledges to the HOTs with Sage as her mother. She susses out her new "sisters" weaknesses pretty easily. Through Sage she meets Stephen Burke and comes up with the free tuition scheme. She brings in Sarah and Mel.
At the same time she starts partying with the DIKs and selling weed to them. Quinn and Vinny hook up, he begins dealing as well and she makes the mistake of letting him meet Buddy. Vinny gets more and more erratic.
Eventually Vinny screws up one too many times and gets caught with drugs on campus. Quinn gets out of it by blackmailing Stephen. Vinny expects Rusty to bail him out with his family connections, but he can't. Stephen covers it up by giving him the chance to drop out instead of being expelled.
Vinny blames the DIKs for "betraying" him, because, well, he's an unstable asshole. He's still talking to Nick, and he hears about the Alpha's smashing their windows, so he pushes their buttons further by stealing the photos of Aerith from the DIK laptop. Somehow he also knows about Chad/Troy and sets up a hidden camera to take the picture of Cathy - he knows it'll hurt both the DIKs in general, and Rusty particular since Cathy helped him in the past. Later he ambushes Quinn coming out of Buddy's.
Nick gets pressured into helping Vinny either out of misguided loyalty, because he's lying about not using anymore and Vinny is holding it over his head, or because he's got some unrevealed grudge too. Possibly he didn't realize how far Vinny was going to go, and now he can't admit he was involved.
It ties up all the loose threads, but having a single overarching mastermind like that can come off as ridiculous if it's not done carefully. We'll see.