"I've already done this all once," Dean said, eyes rolling upwards briefly as if looking for strength. "I've already got the worst deja vu, and if we could just skip past the bullshit, that'd be awesome." He laughed a little half-heartedly when she asked about Crowley. Considering the last time Dean saw him the so-called King of Hell was about ready to confess his sins, the thought of being afraid of him was a joke. "Crowley couldn't find his ass with both hands. Right now, this has nothing to do with him."
Dean couldn't help the mildly put off look at her come on to Sam. Considering that Sam was sans soul, that, well, he didn't want to think about it. When Sam didn't stand down, Dean prepared himself for an argument. Talking Sam out of killing Meg wasn't on the list of things that would usually come out of Dean's mouth, but for the time being, he didn't see any use in killing her. Later in the future, she had their backs more times than he wanted to admit.
"With Crowley hunting all the loyalists down, I hate to tell you this, Meg, but we're the best you've got." He shrugged his shoulders. He knew that Meg was going to twist that statement, but even she had to know it was true. "Until we've managed to get out of here and deal with Crowley, it looks like you're stuck with us."
Unsure if he should tell Sam to back down with the knife, he didn't really say anything, but gave Sam another look. Meg had helped them in the future, and once or twice, was even invaluable. If Sam could refrain from killing her, they'd be golden. "I'd listen to Sam," he shot back to her, with an ever-so-subtle hinting tone. She hadn't dealt too much with Sam without his soul; Dean had. She had to make herself useful to him or she'd be as good as dead. Dean had learned how this messed up version of his brother acted, and he knew that just his word might not be enough to convince him to keep Meg alive. She had to play nice too.