OPTIMUS PRIME has lost a lot of friends to MEGATRON and the DECEPTICONS over the long centuries of the hunt for the AllSpark. All of those friends were warriors and soldiers, though, who knew the price of their quest. This is the first time they've brought their war to an inhabited planet. MEGATRON may not care about the destruction he leaves in his wake, but OPTIMUS PRIME will be rusted if he's going to let the DECEPTICONS harm one, single human.