Scourge! Reformatted from Thundercracker he's the leader of the Sweeps!
Under Unicrons control he too was beaten and abused by the dark lord this left him with a lot of problems when he was freed.
Namely, he lacks any sort of ego/self-worth (So kind of the opposite of TFA!TC)
He's a worthwhile guy beneath it but he occasionally slips back into this mindset.