Dean's glad he can be useful; normally Dad's handling the hunting-killing-rescuing (and Dean doesn't really understand why he can't be a part of that because he's younger and faster and okay, maybe not as strong because Dad's carved from granite or something... except that he does, because someone has to look after Sam) and Sam's all over the research (and it's less of a mystery why he can't help with that side of things, obviously) and he's twiddling his thumbs and making suggestions which immediately get shot down. But talking to Abby is something he can do – just him, because Dad would get pissed off with the random tangents kids take when they're telling stories and yell at her to get to the point already and then she'd start crying and they wouldn't learn anything – and that feels good, and even if they have to go back inside and call Dad to come fight the goat monster (which will suck, because they'll have done all the work and really, how much of a bastard can a goat be?) he'll have helped for once.
So he's working through where to go next in his head, hoping Sam's doing the same, when this Laura Palmroy turns up and starts being disapproving, and from his reaction you'd think it's him she's scolding because he straightens up almost immediately and shifts uncomfortably for a second or two (and bristles, though he's no right to and should realise she's as stressed out and upset as Abby, because hey, the kid's just trying to get her sister back and would it kill her to maybe believe what she's saying?) before fixing the smile normally reserved for cops (aka 'people who do our job but suck at it') and people who think they know what they're on about but are full of shit – not exactly unfriendly, but laced with snark.
And this is normally where Sam would take over, would make excuses for why his brother's being a dick and take the pesky adult aside and get them to open up to him with his silly puppy-dog eyes and fake-earnest smile (at least, that's how it works in Dean's head, because they've never really had cause to put it to the test what with not being allowed to hunt yet, but it works just fine when it turns out that the poker players he's been hustling aren't thrilled to have lost to a smarmy little cock like him, or that the really attractive blonde he's been playing tonsil tennis with has a troll of a boyfriend she totally forgot to mention), and Dean shoots a care to handle this one? glance at the space where he used to be a split second too late. Gulp.
He wants to make some excuses, close the door and go see if Sam's okay (judging from the noise in the kitchen the answer to that is a definite no, and while it could be nothing it could be another migraine and even if it's not the last thing Sam needs right now is to spaz out with an audience). But there's a kid missing, and her big sister's stood in his doorway and no one believes her, and other kids are missing, and if this goat chows down on someone's little sister – or brother - when Sam is alive and something-like-well and close enough he knows he's safe...
… the nagging voice in the back of his head is a small price compared to not being able to live with himself, right?
(He's pointedly not thinking about how different the answer would be if Sam was in danger, by the way, pointedly not adding up how many people could be shoved the the wall if it meant saving Sammy).
So he turns back to Laura, and softens the smile slightly (the half-confused, half-concerned look he shoots back into the kitchen doing most of the work for him in that regard, probably), finds himself using that puffed-up trust me, I know what I'm doing voice he's been trying to perfect for the day when it's him and not Dad trying to convince whoever-it-is that underneath the cheap suit and fake ID it's a genuine Marshall or agent or whatever. "It's no trouble, ma'am, really. You know what kids are like. They say the weirdest sh- stuff"
He's careful to shoot Abby a wink there, a I'm still on your side, adults suck sort of thing, though it's less a tactical decision like dealing with this Laura woman is and more just what feels right to him.