She was an odd duck. Practically an unknown when she was cast as Saavik for Star Trek II. She was a big-time trekkie and it was her dream to be in Star Trek. So, the producers want her back for the next movie and possibly a recurring character. So what does she do? Asks for MORE MONEY THAN SHATNER was to receive for what was going to be her role in Star Trek 3 because she believed, due to her breakout role on TV on Cheers, that *SHE* was now the star of the Star Trek franchise.

.....aaaaaaand she never appeared in any other Star Trek role ever again.