[darkra]

The main character Rip goes on a dating show "The Eligible Arky" one of the participants that wants to date him Ximena is a herpetologist and shows him a new snake she has discovered. The snake bites her and then runs off.

Pretty much from then on every time the Ximena is on screen she appears more and more snake like until she is a human sized snake with small arms and legs.

Unfortunately Ximena does not appear much and all the transformation is off screen but it is still a good transformation in my mind