Originally just one of the J-Team possessing a load of special material designed by Sara, Jet spent some time in Carmilla's Hell of Flesh. Her inability to rejoin with Jade is result of a curse she received there. Now, instead of depending on Jade's charges, she obtains energy to survive like a succubus. During her infernal adventure, she unlocked her power as a shapeshifter.
Her status is still up in the air. I'm calling her a student for the moment, although that might not be accurate.
She's described in Jade 9 - Sit In.
She has a mention, although not by name, in The Second Book of Jobe: Part 2
- watching as Nikki danced around hugging and kissing and saying goodbye to her girlfriends. He watched as she hugged Jade and Jinn, even hunting down Jet and the cabbit to make sure she got the whole J-team.