Sentinel Prime (Earth-9107)

Many times brash, leap-before-you-think types learn a lesson from their misadventures and use that knowledge to grow into more mature well-rounded fighters, even leadership roles.

And sometimes they learn the wrong lesson (or the right lesson the wrong way) and turn out like Sentinel Prime.

While exploring the planet Archa Seven with his friend and successor Orion Pax, and the lady they're both pining for: Elita-1. However, Archa Seven's arachnid inhabitants attacked them, and Sentinel was put in a coma. During this time, Orion and Elita became a couple, and when Sentinel awoke, he blamed Orion for what happened to him since he did not get the girl.

The end result is an Autobot who could be one of the Autobots' greatest assets but such a jerk it's hard to see how. His expandable Skyboom Shield is virtually impenetrable and he's a strong combatant and utterly tenacious hunter. He seems to have Cybertron's best interests at heart... but his perception of "best interests" and how far he'll go for said interests is definitely skewed.

To his core he's still the same smug act-first-think-later-maybe bot he was before, only far more focused. Despite the "stickler for the rules" aspect of his personality that has come from the loss of Elita he seems to use the rules largely to bully his way of doing things on others. He really can't handle the unexpected thanks to a distinct lack of genuine field experience and inability to improvise like others in the Guard. Thanks to that one fateful trip to Archa Seven he has a severe phobia of organics and burning desire to further humiliate Optimus. To his credit, he would never actively sabotage another Autobot... but he sure will make their lives a living hell if he thinks he can get away with it.

When the war started, he vanished, leaving Zeta Prime to lead. But he will return.