Of course everyone sees the similarities of Optimus floating in space to Megatron in the '86 movie, and he turns evil, so as many people have theorized, maybe Unicron is controlling him. My question is, what did Unicron offer for Optimus to accept this? I'm thinking maybe Unicron either pretends to be good and doesn't mention the mind control, or Optimus only takes his offer because he believes the Autobots are in danger and it's his only way to come back.
I doubt it's unicron, but maybe something else, after all he was 'built to do as he was told' and he replied 'I am a slave to no one ' this implies to me that he is capable of being controlled against his will, hence his apology to bumblebee.
Yeah I slowed it down and and the position of the video is misplaced because Optimus Rips off Bumblebee's mouth/chin guard or face before stabbing and probably stabs the floor next to him or scrapes his head but Yeah I think Bumblebee gets off too light in these movies, he needs to get beaten up or more screen time etc
Its not Unicron, but cybertron, more than likely the quints took over cyberton while it was dormante and are using it as a ship to take over earth