OK then I'll give what I can come up with on the spot. Lemme think here...
Alternate universe: Simon and Lupin are partners in crime because Kamina doesn't exist or is too busy fucking Yoko in some foreign country. Unlike Simon's dream world in GL 26 Lupin is actually a decent mentor to the side-kick and since Lupin hasn't met Jigen, Goemon or Fujiko the two are pretty content with their partnership in crime.
This is until they wind up with May, a tiny cyberdoll who's being transported. She is special because she was once a normal robotic toy until she was possessed by a rogue but powerful stand that actually wanted a physical body.
She's unaware of the fact that she's a stand possessed doll and only knows that she belongs to a powerful and wealthy businessman. Lupin, obviously the scoundrel he is, decided to take her there in the hopes of either getting a reward or stealing his reward from the guy and making off with it.
Meanwhile the ACTUAL businessman died a few months ago and is nothing but a dead puppet to the immortal vampire Dio who knows that May's stand is unique in that it can cancel and nullify other stand powers. So he wants to use her or destroy her depending on the concept of the plot.
It all just picks up from there.