"Don't let people do whatever they want with you." Yes, yes- Sae is very aware of how hypocritical that sounds. He just simply doesn't care.

Though, that's how Sae sees most things nowadays, including you for a little while too. But cold and heartless as he is, Sae isn't just gonna sit around and watch people use you for their own entertainment and taint you so.

It's only because you're his younger sibling that he still has some semblance of responsibility for.