Ratchet

"But you can call us ´Autobots´ for short."
- Ratchet to Sam Witwicky. Ratchet joined up with Optimus Prime not to become a soldier, but because he believed the Autobots presented the last and best hope of preserving life in the universe against the Decepticons. He is devoted to saving life, no matter what form it takes, and no matter whose it is.