Ranma is sitting in the Nekohanten awaiting an order that Shampoo is supposed to be serving. Shampoo, being Shampoo, has decided to try a new spice to win Ranma's love and his hand in marriage. (standard plot device because I really can't think of a more creative way to do this) This spice is one however that the amazons have never tested and which they have been forbidden to test by their ancestors, who were guarding it for someone else.
Ranma takes one bite of the Ramen with the spice in it, and collapses unconscious. Shampoo becomes frantic.
At that moment, Cologne returns from the shopping trip she was on while Shampoo was serving Ranma (yes, I know that there's a discrepency in the plot and that Cologne does all the Nekohanten's cooking...but it's only an idea...it can be improved) and discovers Ranma's prone body on the floor and Shampoo trying frantically to wake him up. She demands to know which spice Shampoo has used and when she discovers which one it is (Fruit of Past Life), she disowns Shampoo from the Amazon tribe.
Several hours later, Ranma awakens, but his personality is completely different and it is discovered that he is the reincarnation of a Chimera named Kuronue. Although his personality has reverted to that of Kuronue (that is, he becomes a very sly and very competent thief who has no aversion to tricking people if it suits his purposes) he has retained all his memories as Ranma, and because he can no longer tolerate all the idiocy that goes on around him, he leaves Nerima and goes to Sarayashiki. (This is a Yuu Yuu Hakusho crossover, so at some point, he's going to come into contact with the Reikai Tantei ie. Yuusuke, Kuwabara, Hiei and Kurama...his meeting with Kurama will be particularly interesting as they used to be best friends and partners in crime before Kuronue died)
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That's all I have at the moment...and if I'm not too lazy, I'll think of some more soon. Can someone please tell me if this has been done? I would also appreciate it if someone infinitely more suited to the task would take over the idea.
See ya.
Trishna.