"That's his personality. He's a prickly little thorn." And that made Emma smile softly, because that was her Hatter. So completely done with this place and everyone in it at any given time, but sweet as candy with her and Ruby. "He doesn't suffer fools."
And Emma would likely protect herself behind that, letting Jefferson tell people to leave her alone for a while, letting Jefferson's protective nature and grumbly personality keep them all at bay for a while.
"He might, you might just wake up and he'll be gone. My mom went back, Regina's gone back. They were just here and then they weren't." And while they were meant to be happy, that they were away from all this death and pain, it still hurt like a limb being removed. "I can't lose Jefferson." If he vanished Emma couldn't say what might happen to her.