Alanis Morissette, Versions of Violence
Optimus Prime, Megatron - Movieverse

Energon drips steadily from the wounds both combatants bear, and though grief still lingers, another emotion flows sure and steady in the undercurrents of his spark. Everything they once had, his brother threw away in favor of senseless destruction and death. So many have fallen since, great and small, and he finds himself staring at his brother as though he might be a stranger, a wild thing living outside the reality of the universe. This world is warmth and light like he's never seen before, and Optimus finds himself remembering the very moment war was declared on Cybertron, and the never-ending yearning to protect and preserve he felt then, sharpened then by the chaos surrounding them and honed to the finest of edges ever since.

This same feeling inhabits him now for this bright new world they've found. The rage and thirst for chaos he sees in the other's very core is no match for the calm flowing through his own, and audios cranked to their utmost, Optimus smiles faintly at the rhythmic padding of sneakers on cement, finally finding the heartbeat of another world within the sound of Sam's running footfalls as he strives to keep the All Spark out of Megatron's reach. He narrows his focus and settled on another beat, rapid and erratic, yet undeniably alive, before allowing himself to look into his brother's optics once more.

"One shall stand, one shall fall." The words resonate through his frame and Megatron never even comes close to understand the meaning of those words as he charges for Optimus once more, ever seeking to main, harm, destroy. Optimus serenely accepts the whirling rush of claws and madness, a certainty beyond ken settling within. Cybertron will die today, its last hope erased when the Cube is destroyed. But Earth will live on.

When all is said and done, there is a balance in all things.