From: One Shall Rise, Part 2
As the Autobots consider Megatron’s offer for an alliance, Megatron entertains himself fighting the Unicron avatars. Perhaps the most we’ve seen of Megatron’s alternate mode. It’s a little hard to tell whether Megatron’s comment to Optimus Prime was sarcastic or not.
Despite all misgivings, Optimus Prime agrees to the alliance with Megatron, and they bridge him to their base. A couple of thoughts: