Some time ago, the Joker met with his doctor at Arkham Asylum offering the tantalizing opportunity to write a paper around his journals. Unfortunately, the book was nearly indecipherable without his help, so he began to walk her through it. Joker described each page of his journal to Doctor Yi, until finally he came to a page which he claimed detailed what he might do if he ever met a nine year old girl named Sasha. This, naturally, was Doctor Yi's nine year old daughter's name.