Heaven Cent by Piers Anthony

"Heaven Cent" continues the Xanth series in yet another fun filled, pun filled, book! Prince Dolph, son of King Dor and Queen Irene, and brother to Princess Ivy, is a shape-shifter. He can change into anything you can imagine, which is quite useful, and often hilarious! Dolph is determined to find the missing Good Magician Humfrey, but of course since he's still young his parents have a few objections to that.


 
Dolph and his parents come to a compromise. He can go on his quest as long as he takes an adult along. Dolph doesn't particularly like this idea (adults tend to squash fun ideas) so he determines to suggest a bunch of truly horrible adults so that when he suggests the one he wants, they'll agree out of relief! Unfortunately (or fortunately) his first suggestion is actual one they agree with! So Dolph finds himself semi-reluctantly the traveling companion of Marrow, an enchanted skeleton from the Hypno-guards.


 
Marrow turns out to be the best companion Dolph could have hoped for. They both have the ability to change forms. Marrow can rearrange the order his bones are in, and Dolph's power is more liquid. It makes them kindred spirits in a way, and both of their talents come in handy more than once!


 
Of course, this wouldn't be Xanth if they didn't face a number of unique trials along the way. Women keep trying to ensnare the Prince (what better match can a woman find?), Dolph is frustrated by the "adult conspiracy" (just how DO adults signal the storks to bring babies?), and the group even finds themselves guarding a dragon's nest for him!