It’s a life for a life. Hook is dead and Robin is alive. Robin dies and Hook lives.
Well, the way I was imagining it was that RH gets murdered and then someone tries to pull that card, as in “Hey, RH died a few hours ago…but hades can we make a swap?” Like, I don’t think that would work. But idk, for a switch to happen it sseems like it would have to be intentional, and I doubt RH is going to give up his life willingly knowing hes got two kids. But eh, who knows.
It looks like Zelena might kill Hades hence why there probably be won’t be a trade of any sort but “luckily” Zeus was kind enough to bring Hook back because of all the good deeds Hook has done in the underworld.