Relentless was the killer.
Endless was his energy. Limitless was the extent to which he was willing to push, to exceed. He championed a lost cause, a lost love. This made him dangerous, deadly. It also made him perfect. But alas, perfection is a curse.
For once perfection is achieved, it can never be so again. And once perfection is lost, it can never be repaired, never be perfect again.