like a star, like a firefly

Exactly. D: Vanna iirc said on the forums that he likely didn't touch Wakaba because he needed her stamp of approval before he took Utena for a ride, which makes sense. He'll restrain himself only if it means he can get more later.

(...oh God. That makes a LOT of sense. In episode 25 Touga seemed okay with what he did to Saionji, or he was able to convince himself more that it was for the greater good. Nanami, though? Not so much. D: I still also believe those scenes with him and Akio were Akio rewarding him with dick for throwing people under the bus. And Touga chose to use it as punishment.)

Honestly? I can see it. Just like my fic where he raped Saionji to stop Akio from doing it, except in that case it was a clear-cut sadistic choice. In Nanami's case, Touga was more like "if I don't, he will, she might as well lose it to someone she loves"...but then she didn't want to and he was confused because what DID she mean by love, then?

Ten years later I realize their birth parents can't have been even decent people to sell their kids like that. I can see Nanami wondering about them and Touga telling her they're not worth it.