Hercules fic
From the "action pack" tv series-
Someone [I'm pretty sure it's "our" Ares] gets sent/stuck in the alternate dimension, and he runs around trying to get back. The, er, climax of the story is the alt-evil Herc lays a curse on him, that Ares can't come until he services evil Herc. The other evil part of the curse is that all the other gods are sent over or imagined to be sexing Ares up, but he can't come.
The most memorable other-gods appearances for me in the fic were Aphrodite-she might be the penultimate sex partner, and then Cupid.
Thank you in advance.