Robin- That person would be me! I am bigger and much higher ranked than this guy. I have tried to "educate" him on the mat ( But be nice) to no avail. He does not comprehend it at all. I have been trying to be nice and not be a dick. And believe me sometimes I feel like being a dick.

Mario-1. Good point. He doesn't listen at all.

2. That would work. But it would be every technique ever time. I can see the steam coming from his ears right now!

3.I do like that suggestion! I kinda feel like I am being "used" when I practice with this guy. And he wont reciprocate when he is Uke.

4. He avoids me and the other sempai like the plague. There is a dwindling pool of people that want to practice with this guy in the dojo. He just practices with lower ranked people that "fall" at him whim and don't know how to do the proper technique.

Krystal- I have seriously tried to be "Harmonious" with this guy. I don't hold him hard and he still cant do the technique. He takes his frustration out on his partner which I don't think is cool. Admittedly I do like "Hard" practice and this guy is definitely an "Aikibunny" but I am not preventing him from doing the technique.
I actually did talk to the guy of the mat. I think it was Sensei's responsibility to handle this but he said for one of us to handle this( I disagree). The thing about this is Sensei is watching not practicing with this guy all the time. He doesn't feel anger in this guy or problems we see on the mat. I stated to him all of the frustrations about his sempai practicing with hm on the mat and how he needs to improve his attitude and technique. He just blamed us for picking on him and he is doing the waza exactly right. He told me we all need to change to him and not the other way around. He stated in the other dojos only Sensei could correct people and since Sensei was not correcting him all the time he was doing it right. The talk basically turned into an argument with me pointing things out and him denying all of them. Later Sensei had a "nicer" talk with this guy and I am not sure what he said to the student. He still comes to practice but avoid the other sempai and myself like the plague.
You are right he hasn't hurt anyone...yet. Actually he hurt someones elbow on his test doing one of his weird moves. Another time doing shihonage he pushed this guys arm through a window. His overuse on strength on waza is going to hurt someone. Sensei is not seeing all of this stuff all the time The thing I dislike is our Sensei says just "Be Harmonious" and allows this guy to keep coming. I think my Sensei feels that practicing Aikido will "Miraculously" change this guys attitude. He has been coming for over a year and the water has not changed to wine yet.