If Lust ever brought that point up he'd just challenge it since he was the one who could keep going without ever stopping. He could go days doing the same, repetitive thing no matter what it was. He didn't often grow bored of anything. Greed was just a selfish ass.
He stopped to look at Lust, but then looked right to Greed. He scowled. He had had every intention of leaving and now that Greed had left in a tizzy it was up to Gluttony to find the key; he wasn't about to just leave Lust chained up like an animal. He had some class! He flipped Greed off on his way out and went to look where he'd thrown the key. It took several minutes but thankfully it wasn't buried too deep. He handed to key over to Lust without question. Gluttony was loyal, and probably the least sin-like of them all, and it was moments when he wimped out or gave into something that it showed. And he really didn't care because as soon as he left he'd just go back to his place and stuff his face out of sheer self pity. "Glad you're back," he said gruffly and turned to the door. He almost threw out have fun fucking Greed but he honestly wasn't in the mood to talk about his brother.