I don't know what am I doing but I already wrote it so I guess I'll place it here

Dim moonlight flowed through the window. Young Elrik had trouble sleeping. He was thinking of his mom, carrying drinks in a noisy tavern. He wasn't allowed to drink yet, but he helped with the dishes. Remembering how she maneuered between drunkards to not spill anything, and the way she talked with visitor leaning slightly forward.

He felt like even thinking about it was somehow wrong, but yet didn't knew why.

Sudden creak of the door made boy jump. His mom, tall and well-shaped woman with long curly brown hair slowly stepped into his room, walking towards the boy. Elric thought his mom might be mad at him for something, but the way she sat down on his bed and took his face in her hands wasn't angry at all. He instinctively crawled back from mom, just for her to lean closer, looking him in the eyes.

"I know how you looked at your mother lately. You are a big boy already, aren't you?"

It was indeed his mother's voice. It was his mother eyes, and his mother's hands, but it wasn't her. Something else was looking through that eyes. With a minor effort, she pulled her dress down from her chest, dropping her breasts before Elrik's face. His already quick heartbeat rushed even faster when the woman took his hand and pressed it against her chest, warm and squishy like a bag of water. He saw them only in a glimpse before, but now here they are, in his palm.

Woman shoved her hand in Elrik's pants, grabbing his hot and stiff penis, just to feel warm sticky stuff to come out of it in that exact moment. She giggled, taking off his pants while the boy was petrified by fear and pleasure. Licking off all his cum, she made his cock big again.

"Y-you…you are not my mom…" Elrik's voice trembled.
"Smart boy." Woman lifted her skirt, revealing her gorgeous legs "I can give you everything she can, and more."

Elrik's gaze was pulled down between her thighs. Noticing this, she spread them, making him fall from the bed before her feet. He quickly stood up, in a hustle took off his clothes, and approached his mother, almost as if he knew what he was doing. When he inserted his manhood in his mom, he felt like he blacked out for a second, pleasure was that strong for him.

Slamming himself against his mother's thighs, he felt like he commited a terrible sin, even if this clearly wasn't his own idea. His heart was about to jump through his chest, his shoulders shivered, he breathed loud and often, looking in her eyes, hypnotised by unnatural and unfamiliar lights in them. Soon he came again, but he was somehow still ready to do it again.

"Where is…where is my mom?" Elrik asked.
"She is no more." woman gently whispered in his ear. "But we still have her body to have fun, right?"
"You…gonna kill me?"
She didn't answered. Just smiled.
"Please…make it quick, then."

Maybe enchanted by stranger in his mother's body, or maybe by own will, Elrik continued to pleasure himself using his mom's hole. He knew it was wrong, but there was no way back for him now. Getting buried in her chest, he came again and again inside her, fucking her like an animal.

"Are you satisfied?" Woman asked after Elrik shot another load.
"Yes…"
"You want to see my real face before you die?"
"Y…yes."

Something, like a smoke, started to leave body of Elrik's mother. She slowly relaxed and fell on the bed numb, and on top of her was a horned female figure with a reddish skin and snake-like tail, floating as if she was light as air. She kissed Elrik in the lips, despite second ago being transparent, amd layed him on the floor. She was a succubus, demon feeding on a sexual energy. Mom never bothered to tell rik about them, but it's not like knowlede would've helped him.

Demon spread her lower lips, revealing small skinny spike-like growths in her vagina. Elrik was intimidated, but didn't panicked. When she inserted his dick in her, it even felt good. Spikes didn't harm him that much, only bothering him on the way out. It felt like being washed by a rough washcloth. His blood was dripping from demon's pussy, as she aimed her palm on boy's neck.

Elrik looked back at his mom's body. He wanted his last memory to be of his only woman in his life. One moment, loud crack and a fountain of blood. Elrik's head was rolling on the floor. Demoness picked him, and threwed on the bed, desides his mother. His body continued smashing itself into succubus atop of him, to her amusement.