Apparently, James' cum isn't safe for internal application.

Feeling Lily's calm deep breaths against his chest, James felt the gears in his head start to turn as he came down from the incredible orgasmic high. Was this really what sex was like? This loss of control, the urge, the need to breed his mate-- no, humans didn't do that. To impregnate his partner... it had felt amazing, yes, but James couldn't help but wonder if the pills were affecting more than just his body. Speaking of which, the muscles were a nice surprise, making the other, weirder changes much easier to live with. As did the fact that Lily's uncontrollable squealing and moaning showed how good his cock felt for his mate-- partner. Which reminded James...

"Whoa!" Lily squeaked when James tried to pull out his cock to no avail. His bulbous knot kept them sealed together. "It's still stuck, huh?"

"Seems like," James answered, his voice sounding weird in his ears. Hadn't the pitch shifted? "Sorry about that."

"Don't be. Never be ashamed of your cock," Lily replied vehemently. "It feels amazing, even now." After a short pause, she continued. "You know, you're the first to reach this deep. To think my own step-brother would be the best fuck of my life..."

While she said this, Lily wiggled her hips into James' crotch, making sparks of lust shoot from his knotty dick right into his brain. It didn't exactly help in making the red monster go down.

"Nnnffhuuuck," the dog morph groaned loudly. "Y-your pussy feels too--ngh! Too good, it'll take forever to go down..."

"I don't mind. Let's stay like this for a while, I like how it feels inside me," Lily answered, snuggling back into her brother. James kept his arm over her side, wrist sandwiched between her soft boobs, resting his head on his other arm. They remained this way for quite a while, but their every movement set off wild twitching in either James' or Lily's nethers, the stimulation keeping James rock hard inside his step-sister's snatch. It was the first pussy he had ever been inside of, and his cock seemed unwilling to leave.

James kept thinking about what was happening to him. The fact that he had just frantically banged his step-sister wasn't even the problem, at least not quite. The instinct-driven rutting, the nearly complete shutdown of his higher thinking was. But then again, maybe that was the way sex worked? It was the most primal, primitive and amazing activity two mates... partners could do together after all. Maybe losing control in the face of overwhelming pleasure was normal.

"Uh, James?" Lily's voice cut into his thoughts, sounding worried. "My butt feels weird..."

"What do you--"

Before James could finish, something suddenly, rapidly grew between them and now poked into his belly. Mind blank, James lifted his head and moved the arm wrapped around his sister between their bodies, pushing them apart slightly. The resulting pull on his dick made the lengthy member tingle and twitch and caused Lily to moan once more, but James pushed through the pleasure from his crotch and further along Lily's bubble butt until he could hook two fingers around the thing that was poking into him.

They gasped in unison before simultaneously blurting out:

"Holy shit, I have a tail?!"

"Fuck, you have a tail!"

James pulled until the newly grown appendage slipped out from between their bodies, causing Lily's pussy to down tightly, molding itself to the contours of his aching, bestial cock. He grit his teeth against the sensations - no matter how good the velvetty slippery tightness felt, no matter how much he wanted to abandon all reason and hump his step-sister until he spilled another load inside her deepest parts, the sitiation was too serious. His condition was contagious!

"Ooohohoh, yes! Pull my tail, make me your bitch!" Lily moaned loudly, grinding her ass into her brother's crotch while her golden-furred tail twitched in tandem with her sopping wet cunt. It took all of James' willpower to not fulfil his step-sister's obvious need and keep a level head.

"Lily! Calm down!" He used his free hand to prop up Lily's lolling head and turn her a bit until he could look into her face. The wanton display of pleasure on her feature almost scared him: Lily's eyes were entirely unfocused and rolled up into her head, mouth hanging slack with her tongue hanging out the side. His sister's breaths came in ragged, panting gasps while she babbled barely coherent pleas for him to continue, to fuck her, to breed her.

James could only stare at his step-sister moaning like a bitch in heat, his cock trembling and twitching inside her spasming cunt, mouth hanging slack. Thanks to the **** on his senses, it took James a while to realize that this was once again his doing, his hand still gripping Lily's tail tight. Once he finally understood what was happening, James let go as if it was burning hot. Quickly, his step-sister's twitching and moaning abated as she fell back against James, breathing heavily.

"Fuck..." James breathed, the lustful tingling in his bestial rod slowly lessening. "Are you alright?"

"Alright?" Lily slurred, still panting. "That was amashing! Why did you shtop?"

"You were losing it! You've grown a tail, for fuck's sake!"

"I wasn't losing it, I was this close to cumming! And if it feels this good, I don't care. Hell, I want three more!"

Lily was right in a way, James had to admit. Every last one of his changes had brought him a new level of sexual pleasure, allowed him to give his mate a new level of bliss. If only they were less freakish...

"I don't even remember why I was pissed at you." It seemed Lily interrupting his thinking was becoming a habit.

"Because I made a mess in the kitchen and left you alone," James supplied helpfully, mentally kicking himself right after. Luckily, Lily's reaction was not quite what he expected.

"Oh shit. What time is it? If Anne sees what we did downstairs, she's going to flip!"

James craned his neck until he could see the clock on the wall over his desk, and his heart sank.

"15 minutes, 20 tops," he gave the usual arrival time of their mother.

"Shit, shit, shit..." Lily cursed under her breath. "We need to get cleaning! Can you pull out yet?"

James tried, but to no avail. He and his step-sister were still locked together tightly, and all his **** tries did was arousing the pair again, their breaths growing ragged once more.

"No chance. Okay. Then we'll have to do it like this." Lily stated the facts, and James had to concur. Better to stumble around the house as they were than incur the wrath of Anne. "Only problem is: I don't think I can walk. I can barely feel my legs after what you did with me..."

The sultry, sexy tone Lily said the last sentence in was enough to make James' cock lurch violently.