Megatron waged a battle to destroy the evil forces of the Senate! Then he continued to wage a war against the evil forces of freedom, organic life, and the very idea of an Autobot living. After some life-changing events, he waged a war against the evil forces of his own past legacy. Currently, however, Megatron's revolution has come full circle, waging a war against the evil forces of the Functionist Council!
Megatron is a master planner, constantly a step ahead of any opponent and even ahead of what he wants now, preparing for anything he may want in the future. He has the physical might to overpower most foes but it's his mind who has one-upped three Primes and rival Decepticons. But his cold clinical nature is a front he has to struggle to keep up, as he's quick to anger and quicker to use excessive violence as his answer to any problem. Megatron's trying to change but he's spent such a long time revelling in violence, it may have been a lost cause from the start.
I once told Optimus that I kill for the sake of killing. I wanted to make him hurt me, you see, because when he hurts others, he hurts himself. And the thing is, when those words were in my head I didn't think I meant them; but when they left my mouth, I realized that I did. If the world thinks you're a monster, what does it matter? The world is wrong. But when you start to think of yourself as a monster...
- Megatron