To be fair it is stated that zhenya has inhuman strength, he’s killed all the other agents on mission to find out about anastasia and taekjoo would’ve died but he escaped every time. Zhenya didn’t kill him purposely directly because he was attracted to him and wanted to play around. So even if taekjoo tried to fight back, it would backfire with zhenya hurting him ten times worse.
I felt that too while reading the novel and the only explanation i found reasonable was that Taekjoo wasn't completely against it, he hated that it was forced ofc, but he wasn't totally against it happening because he was getting pleasure out of it too. It's quite a twisted start of their "love story" tbf. Also he was always whipped for zhenya's face card in his inner monologues, so he already thought of him as a handsome man atp of the story

So this trained supposedly first rate agent won’t even fight back getting raped by the same man? If we want to have them fuck there are better more coherent way to get us there.
I’d prefer if we took out the rape and just Mr. And Mrs. Smith this thing. Like they can fight and try to kill each other but ultimately be to horny for each other to not end up fucking. It would be a much better less convoluted read. It’d even be novel because it’s two men having those feelings whilst coming to term with same sex attraction.
THAT would enrich the plot with so much substance.
The rape makes what will likely turn into romance later make no sense and ring ultimately unearned and weird.