It hasn't been too long since Red had to have his testicles completely removed, but I couldn't get him to stop humping things at first. That's not really his typical behavior, even though he is very sexually active. He would not leave me alone one night after it happened, and even though I tried to get him to leave me alone for quite some time, it got to the point where I though he might hurt himself for how hard he was trying, so I just let him do it. He still had staples in, but he did get a full knot, it was actually really good. He seemed pretty content after that, almost like he had something to prove. About a week and a half after that (no staples, healing well) he decided to mount me again while I tried some stuff with the others. It started off well, he did penetrate, but then about halfway through the knot inflating it just stopped. I looked back at him and he seemed a little lost. He pulled out about 35-50 seconds in, but was very happy to be licking/part of the action once dismounted. I'm wondering which way it will go, but I wouldn't be surprised if he became less active.