Adrien Agreste was sixteen when he wandered into Wonderland, and on a whim, agreed to save it.
The Cheshire Chat is seventeen as his bloody head watches the love of his life cut off a man's legs, and promptly pass out.
He feels the smile etched into his face fade away as the Butterfly King's lifeblood pours out, turning from blood to Ladybugs, that fly over the countryside, and for the first time in months, his smirk is real. "We both know what happens, now that Alice has made the life cut."
"You seem excited," the man growls. "I'd think you'd be horrified by what you're doing."
"Not at all," The Cheshire Chat tilts his head… well, himself, technically, considering the head's all there is. "Cat are predators. There's no horror in a cat eating a butterfly."
The king looks disgusted, but The Cheshire Chat doesn't care. If this man didn't want to be eaten, he shouldn't have let his Princess Volpina go around decapitating people. Mass is needed to regrow a body.
He starts by floating down to the legs, already cut off and not moving, and takes a bite out, feeling a bit of his neck regrow, as blood drips from his mouth. The flesh tastes like tough steak, with a but of a greasy, oily tint there. It's not exactly the sweetest thing he's tasted, human flesh, but it's passable, and his body is, bite by bite, growing back.
By the time he's finished with the legs, he already has his shoulders, most of his torso, and an arm grown back, although blood still oozes where the flesh cuts off. He looks down at the unconscious Alice… no, Marinette, stirring, and uses his newly-regrown hand to stroke her cheek. "Sleep well. Sleep longer. Sleep until we've made it home," he whispers, and she falls away from her near-waking state, sighing at his touch. The hand is bare, not leather-coated. His own skin.
He floats to the Butterfly King, and lifts the man's arm, taking a first, harsh bite of living flesh. The man's screams echo through the manor.
…
Body regrown, and the Butterfly King nothing but a blank-eyed head, drained of blood, on the ground, Adrien Agreste peels off the mask and ears of The Cheshire Chat, and instantly feels ill. "Holy shit…" he mutters. "That sure was messed up." He averts his eyes from the head, lifting Marinette in his arms, and steps out onto the Balcony… it's snowing, and in the snow, people stand as if just waking from a nightmare. Manon Chamack rubs her eyes, clear, brown eyes, with flesh hands, looking up at him. "Who're you?" she asks. "What happened?"
"It's me, Puppet Girl," he smiles, but this smile is gentle, bittersweet. "Cheshire Chat."
She stares, and then races to hug him. "You look weird though."
"I know, Puppet girl." He looks up to the other mages… the once-akumas. "Alice saved the day. I'm leaving… so this is goodbye."
"Do you have to go…?"
He looks down at Marinette, sleeping soundly in his arms. "I made a promise." He turns to Vincent Aza, a man with a magic camera. "Will you send us back, Pixles?"
He lifts the camera, and the lens flashes…
…
He lands on his feet, in front of the Dupain-Cheng bakery, and he shakes Marinette slightly. "Marinette… Marinette!" he beams as her eyes open, and she throws her arms around him.
Snowflakes land in her hair. Snowflakes of rebirth, of awakening. The snow that signals the end of the nightmare. She smiles into his chest.
"Princess, we're home," he whispers. "When you killed him, the Ladybugs did their job. We're home." No need to tell her what he did, or what he left behind.
He lets her down, and her feet rest over the hardened snow, as he rings the doorbell.
She's home, and they're together. Everything will be okay.