"Um, okay" James though for a while. He really didn't want to do this but agreed with his new friend that it was the only hope of escaping from the mad magician. His first thought was to become something big and powerful, but he couldn't see anyway brute strength could help him right now. A creature with wings was tempting and might even be quite fun, but there really wasn't anywhere to fly to unless he could get outside. He then looked down at the largish crack below the locked door leading to the next room he and Becky clearly weren't supposed to get into.
"Come on, I haven't got all day!" Becky seemed to know what James was thinking and was willing him to do it "Would you really rather I choose for you?"
James realised he had no option
"A mouse I guess" he shrugged. Becky winked at him in approval.
"Ok, if that's how you want it!" she sneered for effect. Moments later, James felt his perspective change. He was on all fours like when he had been a dog but the room around him was huge this time, Becky's now enormous feet looked like those of a giant to him. He didn't need to see his reflection to know the spell had worked and realised how vulnerable he had suddenly become.
The naked giantess that Becky now was crouched over him and whispered in a voice that seemed to echo all around him "See what you can find, we can plan our next move later. And be careful"
She then rose to her feet an watched the small, white rodent scurry away under the door.