"She wanted to become one." Hold on tight Rita, we're about to go into some dumb. "It was a spell that I pieced out. We made an arrangement: I give her what she wanted, she gave me what I wanted. She wanted to become a cat, so I made her one, and I wanted to learn madness, so she gave me a vessel symbolizing hers."

Oh right, the woman was mad, did he not mention that? Strange frowns a bit before deciding that obviously he must have, why wouldn't he otherwise?

"It was a more impressive bit of magic than I'm describing it as," Strange continues, with a sigh. "It loses some of the flair in the retelling."