I'ma reply to this one at a time. First point Quinn doesn't flirt. With anyone not MC not the clown down the street hell not even Rheona she just pushs her down and sits on her face. On to drugs. She didn't offer him a freebie because she was on the verge of ending up in a ditch somewhere for loseing the bulk of her product. Do you honestly think that Tommy paid for that Heroin she stuck in his arm? No he didn't. BTW if he is a partner in crime they do have freebies between each other thats just how druggies run. Now will one druggy give another an 8th to take home no but they smoke together from each others stash all the time.Except, she's just clearly not attracted to Tommy. She may see him as a friend and a "partner in crime" but she never displays any kind of flirty behaviour around him. Even on the drug part, she didn't provide him any kind of favor. Refusing to give freebie or reduction. Despite her low inibihition, she still has a very pragmatic attitude with sex. During the first season, while she was already infatuated with the MC she still tried to get money from him. During the threesome with Riona she tried to maintain a "professional" facade until the MC implied she enjoyed it despite the fact he had to pay for it. On the roof, she asked money first until the MC made her admit she wanted it too. That was not casual sex because she sought a level a connection with the MC during sex nonetheless. She explicitly said she wanted to be the first girl he fucked while being high and the one he'll remember every time he blazes a fatty. That wasn't just "boning someone under influence".
So if you think she would casually bang Tommy just for fun, without trying to get something in return, you got her character wrong. She has no problem whoring herself if she can get something for it but Tommy has nothing to offer. As for Tommy, he keeps bragging every time he fucked someone ( Tania or Arieth for example ), if he had fucked Quinn in the past he would have mentioned it in front of the Diks. On the contrary, he was stunned in disbelief when he learned the MC fucked Quinn. A reaction he wouldn't have if Quinn casually had sex with anyone. Sure, he has a soft spot for her. He was deeply hurt when she "backstabbed" him about the prep party and swallowed his pride even apologized to her but she didn't play along. Refusing to apologize in return and even tried to charge him the double.
On the other hand, Quinn and Vinnie could have been a thing. With DPC sense of drama, I wouldn't be surprised if he was her former boyfriend before they started being rival dealers.
There is also a Mole in the Diks I'm pretty sure he would have give himself his own DIK CODE on fucking her as he's been outed by was it Jamie once for breaking their rules once before. And as ive said before Heather and Quinn hate each other she is on the Veto list 100%
And the only reason he was charged double like everyone else is because if she didn't she thought she'd be found in a ditch somewhere because she just got fucked out of her last stash of product it wasn't personal at all it was hey you don't want me to die do you? Without her saying that but thinking it pretty fucking hard. During that week had the MC asked for weed he woulda been charged double too.