The hell had given three chances to Zach. The first was to leave hell with Asmodeus and never return. The second was to sacrifice Asmodeus and defeat Nirn. And third was to have sexual intercourse with Asmodeus and enter the inner hell.
[What do you say? It's the best and the easiest offer yet. You just have to make love with her, and that's it.]
Indeed, it was a simple offer, but it was something Zach would never do against Asmodeus' will. Even if she was constantly trying to mate with Zach, that was because of the aphrodisiac effect.
Out of all three options, the first one seemed the easiest to Zach, which was to leave hell with Asmodeus, never to return. However, he couldn't do that after coming so far. The second option was out of his choices, so he had to make do with the first and the third option.
[You don't have the liberty to think, son of Deus. We both are short on time. Will you do it or not?]
"How can you ask me to mate with my sister?"
