Stepbrother escalation! Forbidden, but GEIL! Extreme 3!

I visit Holly Banks at home, completely relaxed. We're sitting on the couch, laughing, talking - just like two girlfriends. Then she casually tells me that she's just had an exciting experience with her flatmate. I get curious, ask... and suddenly everything feels a bit different. Is he still there? A question I shouldn't have asked! Suddenly we're in his room and things escalate completely. Is it forbidden? Maybe. But is it still hot? Oh yes, and how! Have we gone too far?