First time writing any sort of erotic stuff, so let me have it.

Cassie O’Donnell woke up on Saturday to the sound of her alarm, face pressing into the sheets and a tangy taste in her mouth. As she had every day since puberty.
She pulled off the covers and sat up, breasts resting on her head, as the phone continued blaring Metallica at the only proper volume for Metallica. Reaching for it with one hand and rubbing her neck with the other, she turned it off and made her way to the bathroom.
The redhead pushed her hair out from around her neck, continuing to rub first with one hand, then both. She cracked the door, pressed her neck down, and opened her mouth, letting the old semen out into the toilet.
“Blgh, I had hoped I was done with wet dreams,” Cassie muttered, her Irish past giving a lilt even to her complaint. She grabbed a cup of water, bringing it down to her face and taking a sip. She swigged it around and spit that in the toilet as well, then grabbed some lotion and rubbed it on her neck. She had time, right? Since it was the weekend at all. And she did need it unless she wanted a concussion from the twins. One of the downsides to her condition.
Cassie was a mutant, one of the first born in Ireland after the PRSM accident in Los Angeles. The airborne virus saw fit to rearrange germ cells all over the planet. In most cases, as in Cassie’s, the rearranging didn't stop there.
Cassie, like most mutants, was born a true hermaphrodite, with a full cock and balls just in front of her lower folds. But where most with a dick had a head, she had a head, the one most expect on top. Instead of that, between her shoulders she had a second pussy, one already beading with juices in anticipation.
So she massaged her neck, feeling the veiny organ swell in response, and moaned in pleasure. Her back pressed up against the door as pressure built up in her shaft. She pulled and tugged. And pulled. And tugged. And…
Ecstasy.
She soared. Sperm shot into her mouth, the salty-sweet taste pouring in. Her pussies drooled in sympathy, wetting the floor and door. Riding the waves of satisfaction down back to earth, Cassie basked in the afterglow, swallowing the rewards of her endeavor with relish.
Her neck started to recede, so with a quick scrub she cleaned the lotion off. She looked in the mirror for a quick inspection- tank top a bit wet, pajama pants soaked, but all recoverable- and stepped away from the door to grab a spare towel.
The mess taken care of, she stepped toward the shower when she heard a knock.
“I'm about to take a shower, who is it?
A man's voice responded. “Gotta brush my teeth real quick, Cass, can you open up?”
Cassie sighed and opened the door, letting her “normal” little brother in. Before he could enter, though, Jared blushed and spun around, faking a gag sound.
“Dude, you forget you're going commando?” he muttered.
“What's that supposed-” she felt the area between her shoulders… and blushed. She ran for her bedroom, hand covering herself, fishing for a pair of panties. “You saw nothing, hear me brat!?”
“God I wish.” She heard him brush quickly. “All yours! I'm gonna go bleach my eyes now.”
“Yeah, yeah, bite me. Have fun at work,” she said, looking back past her hip. Christ, where was last night’s pair? She didn't bother with a lower set at night, but the last thing she wanted was to flash her brothers and sisters. Any more than she had to, at least- breathing trumps modesty.
Eventually Cassie just grabbed a towel and threw it over her shoulders. A little chafing, but it was only until she made it to the shower. She snuck in and locked the door, starting the water up to make sure nobody else knocked.
Throwing the towel aside, she stripped, taking extra care to pull her head through the pajama flap. Checking the door one last time, she stepped in.
Cassie hummed a little tune as she soaped up, her hands exploring her odd body as they worked. She tried not to start herself up again- she already needed to clean her pipes after the shower, and that was an experience she didn't really like dealing with more than necessary.
Which would be so much easier if the warm water wasn't hitting her top puss, already raring to go after her earlier fun. Maybe if she was quiet…? She shut her eyes, and felt her neck stiffening. Not thinking with the little head was hard when it was your only head.
The young hermaphrodite sighed, and soaped up the full foot-long span of her dick, enjoying the slickness against her sensitive skin. One hand remained on her neck, angling her face into the shower, while the other rinsed off, then dove into the plush folds of her upper lips. Cassie blushed as she daydreamed, plunging face first, deep inside another woman, tasting the warmth and sweetness of her lover’s insides all around her, while a handsome man churned her upper vagina with the same passion and intensity. Her hips bucked, thrusting herself deep into the imaginary pussy before her, and she moaned as her other hand copied her cock, plumbing the depths of her slit. Lost in her fantasy, she settled into a rhythm, matching the pump of her hips to the thrust of her fingers, panting in lust as she strove to fill her lover with her seed. Her normal pussy ached with need, and Cassie idly wished (not for the first time) that she had enough arms to satisfy all of herself at once.
A heady warmth built in her throat, and her upper lips pulled her hand in deeper, almost suckling their own juices from her fingers. Finally, her mouth opened in a gasp, and white burst forth from her lips, covering her face and spraying the shower head. Her upper cunt tightened its grip as her first orgasm pushed it over the edge, gushing over her shoulders and into her hair.
For minutes, Cassie was lost in orgasm, her mind only barely aware of the world beyond her body. It was only when the water started scalding that she was shocked out of her daze, and heard an angry pounding at the door.
“Cass, hurry up, other people need the bathroom today!”