"I don't know." Birkin picked the beaker up again, taking another drink. "I personally wouldn't want to be leashed like that. By anyone." He frowned slightly. "What did Shinigami do that makes you feel like you owe him anything? It's nice that you're fond of your students, but what about yourself. Aren't you and your desires more important?"

Birkin sighed. "But then, I wouldn't really want to be a toy either..." He bit the inside of his lip, looking for a slightly less depressing topic. "So how did you get that?" The scientist pointed at the scar on his companion's face to clarify.