my spirit just never learns
Emeralda was a curious creature - made to service others' desires, in some sense, just as Id. He would not deny the kinship he felt for her (well, only outrightly; he would act on what he felt even if he wouldn't say it).
She couldn't, or perhaps only didn't, wouldn't, shouldn't, recognize it as Fei's Kim, or Kim's Fei, or Kim's Id, for that matter - or Fei's Id, of course, for the very same. It took more explanation than Id would have liked, but eventually she was convinced to recognize wild red hair.
And thus began the begging for piggyback rides.