all forms have a step by step guide for how to get them in the walkthrough! here is the one for princess:
Elami’s perfect princess (Lewis): this scene will play if during the second mingle phase, female Lois is marked, not in a conflicting form (maid, spy, dalmatian), and Elami has more than 3 influence. Trigger the scene by entering the lion's den area. In this scene, Elami will enact a plan to turn the bastard Lois from a shameful child, into a lioness princess.