Caduceus was recruited by the rest of the Mighty Nein to help free Fjord, Jester and Yasha from Lorenzo. Caduceus joined the Mighty Nein after completing their goal. Fjord was initially put off by Caduceus, given that he had more weird traits, and comfort with death. The two bonded for a bit during their time while searching for answers to Fjord's patron, Caduceus even going out of his way to find out what happened to Vandren.
The two started to bond more after Fjord started to show interest in Caduceus' goddess, the Wildmother, after she helped stop U'kotoa from entering his dreams for a short while.