Quote Originally Posted by GoktimusPrime View Post
Even just within the movie universe it's a contradiction. As I said, TF1 Prime showed compassion -- he only killed Bonecrusher as he was fighting him (i.e. it was NOT an execution), and he expressed regret that Megatron died at the end. Prime's attitude in Shanghai flies against what we saw in Mission City. Is it the same Optimus Prime?

Yes but at the time Demolishor was executed he was fully incapable of causing any more harm. Thus at that time there was no need to kill him. And if he was beyond repair, this should have been pointed out to the audience because otherwise it does look like an execution. Prime didn't even ask Ratchet to scan him or something, or even bend over and have a close inspection... *sigh*

Instead of saying, "Any last words?" he could have said, "I'm truly sorry for this." -- some kind of expression of regret. Without that then it does feel cold fluided.

Yeah but you'd expect Optimus Prime to rise above petty feelings for revenge and act PROFESSIONAL.

For example say there's a guy who walks into a building and shoots innocent people, then the police arrive. Unless he's immediately threatening a life they're not going to get police snipers to take him down. First they're going to ask him to surrender. And if he DOES surrender, or say a cop shoots him in the leg and incapacitates him, would you expect the police to walk up to him and say, "Any last words?" before shooting him in the head at point blank range? Or would you expect the police to arrest him? If the police chose to shoot him, what do you think would happen to that officer?

Soldiers get into massive trouble if they abuse POWs in any way (e.g. humiliation, torture etc.). And the execution of POWs is considered barbaric.
I've interpretted the scene differently to yourself. Rather than simply being incapacitated, I see a Decepticon in a great deal of pain, beyond repair and close to death. The only thing Prime could do was to 'put him out of his misery' so to speak. He knew this and that's ultimately why he introduced Demolishor to his little friend. Perhaps he could have said something a bit better than 'Any last words?' but this is a war and sadly not everything happens the way it should. I actually think it makes Prime a bit more interesting and less predictable than usual. *shrugs*