Really no one here, who knows it can by joy to hurt someone?
The joy of demonstrating ones power, ones might.
Or joy dominating someone and being able to ...
So if you don't know feelings like this, why do you practice a martial art?
Why do you practic techniques which will hurt, maybe badly your opponent? (hiji kime osae, irimi nage, atemi nage ...)
Do you really feel no joy when controlling uke?
But then, half of aikido is being controlled...but then: I thought - from my lofty position as 5th kyu - that both partners in aikido are practising aikido - you both yield, and are in harmony, and both avoid destruction/harm: you are both in control, and the point of ukemi is to safely avoid harm - uke stays 'live'/alive....?
I mean, I don't get how anyone can choose aikido for the purpose you describe: I know that there are those who saw o'sensei as an incredible martial artist, but they're gone, and now people tend to see the most effective MA as one in which there are strikes, and competition, etc.
The fact that aikido, prima facie, is purely defensive, surely sees that those looking to gain joy from dominating and having power over others, like a serial killer, choose something more aggressive, more amoral as their martial art...?
The point of aikido techniques is that you don't badly damage your 'opponent' - there isn't even an opponent, in fact: you are meant to yield to the other person, which necessitates having compassion for them.