"You know," Said Kat, "I think making out with Dan is the perfect role for you. You just haven't realised it yet."
With a wave of her wand, Sandy began to change. Her clothes began to seem massive as she shrank down to roughly half her height, leaving her at eye level with Dan. She struggled to get out of her now oversized clothes, but her hands didn't seem to want to cooperate. The reason quickly became apparent as her arms withered away and withdrew into her shoulders.
"Kat, stop! Don't hurt her!" Dan protested, but Kat just patted him on the mound
"Don't worry, little pussy, I'm not hurting her. I'm making her what we all want. You want to still be her lover and she wants the same. Thats utterly adorable, so I thought of a solution." She said, walking over to the shrunken girl and helping her out of her oversized blouse.
The rest of Sandy's clothes had fallen off already when she shrank and with the blouse gone Dan could see that where Sandy's arms had been there were now just bare shoulders completely devoid of any evidence that she had ever had arms to begin with. Her shoulders wriggled as Sandy tried to come to terms with the change.
"Wh-What have you done to me?" Sandy asked in shock
"I'm making you into my familiar." Said Kat "That way we can always be together and you can stick by your precious Danny as he lives his new life between my legs. I just have a few finishing touches to make. A familiar is supposed to be an animal, but Dan's pervy little animes have a solution to that."
She waved the wand again and Sandy squeaked in shock as a fuzzy black tail began to grow from her behind and her ears migrated to the top of her head, becoming furry and pointed. Her eyes changed as her pupils became slits and her shriek instead became a cute mew. Soon the change was complete and Dan realised that Kat had made his girlfriend into a tiny armless catgirl.
"As my familiar, you support my magic and service my needs. And right now, my needs are that you service Dan"