Luther

Luther was the knight who raised Lion El'Jonson on Caliban and later broke the planet trying to keep it. He was the Lion's father in every way that mattered except blood, and that gap became a war.

He led the Caliban garrison into heresy, shattered the homeworld, and spent ten millennia in a cell in the Rock while his sons became the Fallen. The Unforgiven built their entire secret on not asking him the last question.

The Lion woke and found him still there. Whatever passed between them is not a sermon the Chapter recites. Caliban is dust. Luther is the man who survived it.