Dex is a character from Zoë's college days, and the first K I T T E N storyline.
First seen in The Time Machine (chapter)[1], Dex is a hunky (yet very shallow) guy that Zoë has a crush on, and who Angela had dated in the past.
Soon after his first appearance, he takes Zoë out on a "date", where she realized he was only interested in her because he thought she could introduce him to Dr. Lorna[2]. Later, he reappears for Love Potion (chapter), where Gwynn uses a love potion on him to try and get him interested in Zoë (as Gwynn's way of trying to make Zoë more comfortable with her using magic)[3]. However, the love potion spell goes horribly awry[4].
We next see Dex in the K I T T E N storyline, where he has finally decided to make a move on Zoë[5] (his efforts are largely ruined by Torg and Angela, with help from Bert). Unfortunately for him, he soon meets his demise at the claws of the EVIL[6].