(In this example, I'm the MC, Jackson Tegu is playing Castidad the Ghoul, and Chuck is an NPC)
Backstory
Castidad Torez has a condition. That's how she understands it. Every six months or so, she goes to see the doctor, he puts her under, and she wakes up looking different. No one's explained to her why in all the family photos it's like she's an entirely different person from year to year. She doesn't realize that she's dead.
Castidad has some problems. Some "emotional stability issues." That's why her family had to move to Finlay, Ohio. Because she got expelled from every single school in their old home town, and they needed to move.
Castidad Torez is a Ghoul
She hungers for chaos and fear.
She has: Obsessive Hunger, What the Right Hand Wants.
The Scene
Everyone's at a party, down by the swimming hole. Fights are breaking out amongst the jock kids. The stoner kids are getting stoned. Castidad is all alone, off at the edge of the party, leaned up against a pick-up truck.
Chuck is a jock, and he gets into a fight with Farley (The Chosen, another PC). Farley lays him out, and so Chuck storms off and leaves the party. Castidad's leaning up against his truck. Bloody-nosed and embarrassed, Chuck snaps at Castidad, "Listen, either get in the truck or get the hell off it." To Chuck's surprise, Castidad shrugs and climbs inside.
Chuck's driving away, his nose bleeding like crazy. He flips on the radio, saying tersely, "You better fucking like country." Castidad gives him a weird look, and then twists the volume knob to max, while saying, "I love country."
I narrate that Chuck's clearly not attracted to Castidad, but he's sizing her up and trying to decide whether he wants to fuck her anyways. I don't remember what happens at this point, but I know it involves some (character) confusion about what the phrase "maybe I should take you home" means, and then Chuck's undoing his seat-belt and unzipping his fly.
Jackson's face gets deadly serious at this point. He narrates Castidad leaning over, and pressing her right hand down on his knee, hard - forcing him to accelerate. As he speeds through a red light and gives her a startled look, she just looks back at him with fire in her eyes. "I'm going to bite your dick off. Seriously."
They're driving pretty fast down a narrow residential street. Chuck freaks out at her batshit-crazy proclamation, and shoves her away. Jackson asks, "So, he takes both hands off the steering wheel to do that, doesn't he?" I nod, sure.
"Well, Castidad grabs the steering wheel, and as she's flung back, she yanks the wheel down to the right, hard. I want to drive this truck straight into someone's living room."
It's about now that it clicks, for everyone else at the table, what's going on here. Castidad is feeding on fear and chaos. This is precisely what she came to the party to do. She hung around by the cars, waiting for a drunk driver to offer her a ride. And then she fucked with him, freaked him out, and crashed his car.
"Alright, Castidad, roll to lash out." 10+. Castidad is beat up pretty bad, but Chuck goes flying through his own windshield into the living room that they drove into. A startled housewife comes down to see a truck where her sofa usually is, a teenage girl sobbing inside that truck, and a dead boy with his pants around his knees (laying on her nice hardwood floors).
Castidad climbs out of the truck. And then, without a trace of guilt, she lies, "He tried to rape me. I did the only thing I could."
And So
That's an example of a Ghoul feeding. Castidad wasn't at her Darkest Self in this scene, she was simply a cold-blooded killer.