Ratchet listens quietly for a long moment, an odd lump pressing down against the tops of his tanks, tightening his throat.

"You were siphoning your own to keep him alive." It isn't a question--Ratchet knew the symptoms of long-term lack of fueling and Megatron's had been bad even for a laborer of his caliber. He puts the brush down and cycles his vents shakily for a moment, a disorientingly strong wave of pain and grief and anger washing through him at the loss of a mech he'd never have met even if he'd known of his existence before today. It takes him a moment to steady himself, his mouth crimped taut around the corners.

"I'm sorry," he says, and he sounds like he means it. "I'm sorry you never knew exactly what happened."