Patrick isn't Jonny.
That isn't the only reason Gerry's fucking him, just the most important one right now. Patrick isn't Jonny, so it doesn't mean anything if Gerry hurts him, biting into his shoulder, fingers wrapped around his wrists. It doesn't mean they have to talk about it in the morning or that Gerry is still interested in hurting people. It doesn't mean anything other than Patrick invited him up, made a joke about etchings, and is now hurting for him and submitting to him. It doesn't mean he's hurting the one he loves again. And that's all that matters.