Honestly just ANYTHING with Caduceus praising the hell out of Fjord and Caleb and telling them how good they are. Both of them need a self-esteem boost.
I'm thinking service top Caduceus, and the other two being pleasured by both Caduceus and each other at Caduceus's instruction, but go wild, I'd be over the moon with any sweet positive-vibes sex with these three together.