aroace Caduceus goes into a powerful rut and is just miserable in general, resenting the way his body and hormones take control. Fjord offers to be a warm hole to work his rut out with as thanks for everything Caduceus has done for him

+platonic sex, with Caduceus seeing this as just another bodily function to deal with.
++trans fjord
++mild objectification elements
++Fjord enjoying it more than he expected
+++non human genitalia
+++Rough sex

--scat or watersports