Impatient, Rex isn't one to think of his actions in the greater scheme of things more focused on a short sighted end goal. He doesn't see things that way claiming that Rip isn't nearly as smart as he thinks he is. To enact his revenge Rex got rid of the Time Masters (stating that he killed Bonnie himself) except Rip Hunter whos' true identity he could never discover. Unfortunately for Rex bragging was yet another rule he broke. This would later prove how he overestimated his value to the rest of the Time Stealers once he was captured by Rip. They decided to kill his infant self in his crib to prevent him from talking. The results weren't what they were expecting.
My take: Personally I liked the addition of Rex to the Time Masters mythos. He shows how important it is that you have the right people in charge of such an important mission. While he doesn't think of himself as a bad guy his stubborn refusal to listen to his teacher feels very true to life. I'm an art student so I've come across (and been a little) like this myself. There are little things about the character that aren't revealed but are hinted at in the story. Jason seemed to be more than a little obsessed with Rip to the point that he chose for his new identity to be as close to his as possible. Rip refers to him as a kid though it's apparent that Rex is an adult. I don't see Rip as the sort to randomly call people kid that aren't as well versed in something as him. This leads me to assume that Rex was a younger age (likely a teen like Corky) when he was a student.
First Appearance: Booster Gold Vol. 2 #4