Circe exists in 3P.  She still TFs people.  She also is one of the few beings who can transform people with marks other than hers.

As Nathan is finding out here, having a mark is no protection against her magic.  Should've gone with Moly instead, Nate!

Compositionally, I wanted him to be looking back at his hindquarters while struggling to maintain balance, knowing that once he was on all fours, he wouldn't be getting back to being bipedal.