I loved The Assignment. It was by far the best acting Rosalind Chao ever displayed on Star Trek. Possessed Keiko was terrifying, especially while pretending nothing was wrong. I can certainly understand why they wanted to bring the Pagh-Wraits back after this episode, but why they felt the need to do it in such an idiotic, cliché manner I have no idea. The Pah-Wraith here is subtle (not about her intentions, perhaps, but very much in how she's acting, with no-one but the Chief ever realising something's wrong with Keiko) and cunning. Imagine if Keiko had come off that transport with red eyes and a stupid voice, how long do you think it would've taken anyone to clue in?