Of course he knew all that. He'd listened to the stories just as much and it would be a lie to say it hadn't been a source of conflict before he'd made this choice. But even knowing that....

"I know." He answered quietly, closing his eyes. "... But my home is already under the rule of a great evil as well. One that has already begun to spread to the stars and will continue to do so until it has consumed all worlds if it is not stopped."

He turned to her, bowing his head.

"I promise, I will not abandon this world to the Calamity and I will do all I can to defeat it as well," he sighed heavily, "but I made a vow to my father and my homeland that I would not rest until I found a way to destroy the evil that destroyed them and restore peace to my world. Even if it is impossible, I must try."

It was a vow he could not break, even if it meant taking on the burden of two worlds. Surely, Rukia could understand that much....