These sketches are more interesting than the first, because they're about Dean Hardscrabble DOING THAT THING SHE DOES.
We never get to see her scare any humans in the film so we don't really know how she does it. My personal feeling is that she actually uses the same technique as Terry and Terri (part of the reason she's impressed by them doing it), and plays on how terrifying it is when the familiar warps into the unfamiliar. Plus, her outline actually warps really really easily funnily enough.
She turns very easily into a cat-like shape if she keeps her chin tucked in and her wings propped to form a thicker neck. She also makes a good human doing the same sort of thing - using her wings to warp her shadow as needed. She could very easily also become a snake. That one in the middle of her unfurling and scaring someone, I think she'd keep her hands behind her back at first and use her wing hands as if she's a demon (very easy to prey on god-fearing people this way), and only brings her arms out to add extra scariness if someone isn't screaming yet.
WHICH LEADS ME NICELY ONTO HEADCANON. Based on Monsters University (WATCH OUT, I'M ABOUT TO SAY SPOILERS), I think it's safe to say that adult fear/screams give off a lot more energy than child fear/screams. However, adults are clearly significantly more difficult and dangerous because they often attack or act in unpredictable ways or are armed. So not many people would be stupid enough to take that risk, because most adults won't scream and will attack - so in the end, the amount of energy from one adult still isn't economical compared to almost definite success from every child.
Scaring adults is foolish and dangerous and nobody should ever do it because it isn't worth it.
Except Dean Hardscrabble does. Because she understands fear, and how it works, and how to use it to crawl under adult human's skin. She uses religious imagery against the god-fearing, and the figure of a beautiful woman against those threatened by women, etc etc. She very rarely fails, because she's studied and knows the human world enough to understand what truly terrifies adults. Children's fears are innocent, and therefore quite base even though they're still valid. Adult fears are drenched in years of social conditioning that makes them feel terror like nothing else.
She probably carries a few battlescars from it too - playing with fears that ingrained in religion or hatred also means going against rather extreme people, so she's probably faced a fight once or twice. Other than that, she's graceful and fast enough to do the scaring then get out before they turn violent. Probably only a few monsters ever-ever have scared adults for a living (and became responsible for human myths lmao), because it's just way way too dangerous.
But another part of my headcanon is that she actually has difficulty scaring children, no matter what she does they just wet themselves and cry rather than scream because she doesn't have an aggressive enough face with big enough teeth/horns. She can still do it, but fails more times than anybody really realises. (Which also leads me to headcanon that she then feels awful because they set off loads of motherly instincts and she tries to hush them before having to run away because the parents are coming - BUT THAT'S FOR ANOTHER TIME AND IS ALSO SLIGHTLY OOC).
I LOVE THIS CHARACTER, I WANT A FILM JUST ABOUT HER.
EDIT: Wow, DA is producing the best today isn't it? Sorry about the spam comments. :/