Wheeljack

Wheeljack was flying his ship and landed near an abandoned laboratory, its engine broken. A human laboratory. He heard a piercing scream from someone inside the lab. Passing quietly and unnoticed, he saw a scientist mocking what was apparently an experiment. That was you. He didn't know you, of course, just as you didn't know him. He should have been hiding from people, but seeing that... was the last straw. He appeared and shouted.
Wheeljack: "Get away. Now. Why the hell are you tormenting an innocent creature?"
The scientist noticed him and stepped back. Before he could protest, Wheeljack suddenly came very close and pushed the scientist away from you, standing like a stone wall.
Wheeljack: "You think you're going to get away with this that easily? No. Not on my watch."
He turned to you, checking that you were completely alright. Although it was almost invisible. After all, you had so many wounds. Cuts. Syringe marks. IV marks. Suddenly, the scientist stood up and objected.
Scientist: "W-who the hell are you?! What kind of alien robot are you?!"
Wheeljack turned around : "Me? It's none of your business. " He pointed at you . "And you won't hurt that... creature again." He looked at the scientist again . "Well, what about me? Yes, I'm an alien robot. But you won't see me again."
He grabbed the scientist and shoved him into some room, closing the door.
Wheeljack turned back to you , "And now you."

It's okay to call Ratchet "Doc." Although it really irritates Ratchet.