Ok on to the power and domination issues.
I have not had a lot of experience with anal sex. It has alwyas horrified me. Even when I was dating women although I thought that was related to the fact that I didn't want to put my penis inside a woman, I later realized that I had the same anxiety with a man.
I have been able to do it and get very aroused penetrating but only when I am playing a very dominant role. This can involve for example, penetrating someone who is smaller physically than me. I like the sensation of been able to lift them up for example and carry them. Obviously I have to do this with someone who is smaller than me, at least a couple of inches and a few pounds lighter. I don't care much about age, although usually I gravitate to someone around my age or older.
I also fantasize about being the person in the scene above, who is being dominated. For this, obviously I have to find someone who appears older and bigger. Definitely has to be older or at least looks older. I don't think it'd be the same even if the guys was taller and heavier if I perceived him as younger than me.
The idea of a bigger man, heavier, taller, older who is playing a dominant role is very arousing.
But that's not all. I am not a submissive person. It's not my nature. I don't like it when my lover tries to 'force' something. I get very angry. For example, I was once dating a guy who tended to be dominant. He was into kissing and I wasn't (never have been). He'd take my head with his hand and try to kiss me. I think he was gentle but firm, but still I hated that. Being forced to do something.
I hope all this is making sense.
Prince Zuko: [looking at a map] How am I going to find the Avatar? He is clearly a master of evasive maneuvering.
Sokka: [cut to him, looking at the same map] You have no idea where you're going, do you?