"You will transform into a werewolf whenever you are sexually aroused." Sam growled as his face pushed out into a lupine muzzle.
Excited to experience his first transformation, Brody got onto his bed and bent over on all fours, presenting his ass to Sam. Sam, now fully shifted to his wolf form, walked over to Brody with a new appreciation for his round and supple ass. He knelt down at the foot of the bed, grabbed Brody's hips and spread his cheeks apart, exposing Brody's virgin anus. Brody gasped as he felt a sudden pressure on his asshole. Sam eagerly ran his long lupine tongue along Brody's ring, encouraged by Brody's moans of pleasure. The musky taste of Brody's ass was arousing him even more then that of Jennifer's musk.
Brody, flaccid from blowing his load inside of Sam's mouth, slowly started to get hard again. Each stroke of wolf tongue sent a wave of pleasure throughout his body causing him to slowly get more and more aroused. As Brody continued to be rimmed by Sam, he felt fur starting to grow on his crotch. He let out a groan as his ballsack started to swell with lupine seed until his testicles were each the size of large eggs. With each passing second, the fur spread up his now-fully erect penis before it joined with his stomach to form a sheath. From it, inch after inch of glistening red, pointed, bulbous wolf cock emerged, throbbing in time to his heartbeats.
Once he thought Brody's hole was relaxed enough, Sam moved his muzzle away from Brody's butt. The two boys were now fully erect and very aroused. The rimming had really fired up the two. It took Sam a lot of willpower to stop the wolf part of his brain from pinning Brody against the bed and mindlessly pounding away at his ass.
"You rrrready?" Sam growled.
Brody lifted his ass higher into the air. "Please," he whimpered, "I need you inside of me."
Sam got onto the bed and straddled his legs behind Brody's. He guided the tip of his lupine penis dripping with precum into Brody. Brody let out a needy moan. Sam's cock felt so much bigger than before. Sam pushed into Brody as far as he could; just under half his wolf cock could fit inside. Then, he pulled out before thrusting in again.
Each time Sam's cock thrust into him, Brody felt his transformation into a werewolf progress further. His body grew in muscle mass. Brody's human body was now built like an athlete. Fur began to spread out from his crotch up his back, across his abs and on his chest.
Brody tightly gripped his bedsheets as Sam continued to thrust his dick deep inside him. Sam's cock only fit a few inches deeper than when they started. Fur reached his hands and feet, razor sharp claws pushed out of his fingers and toes, replacing his human nails. Fur continued spreading up his neck and across his face. Brody's face started to push out into a muzzle while his ears grew pointed and moved to the top of his head. The final part of his transformation was his tail.
Sam saw a small tail starting to push out of Brody's tailbone as he rammed his cock into Brody. After it pushed out to a foot in length, he reached out to grab it causing Brody to moan in pleasure. Sam passionately humped Brody and pulled at his tail until it grew to its full size. At last, Brody had completed his transformation into a werewolf. Sam pulled Brody's fully realized tail as hard as he could, creating leverage that allowed his wolf cock to be fully engulfed in Brody's ass. As Sam ferally bucked against Brody, he could feel a pressure at the base of his dick. It was his knot. He could no longer resist the feral instinct inside of him, the one telling him to breed his mate.
"Rrrrr... Brody," Sam growled, "Your ass is so tight! You sure you can take my knot?"
"I can handle it!" Brody moaned, "Knot me! Please!"
Sam collapsed on top of Brody and started thrusting more forcefully. Brody howled in pleasure as Sam's half-inflated knot pushed against his anus. He pushed back against Sam, feral instinct leaving him desperate to be filled. With one powerful push, Sam shoved his knot inside of Brody. It rapidly swelled up to its full size, locking the two wolves together. Sam continued to make small, rapid thrusts against Brody.
Brody's asshole clenched tight against Sam's inflated knot. Sam growled due to how tight his cock was being squeezed inside of Brody. He reached under Brody's body to stroke the new wolf's cock. Brody let out a bark as his balls nearly retracted into his body. The pleasure of being deeply penetrated and having his dick stroked was too much to handle. Brody reached his orgasm and started to shoot several strands of lupine semen onto his bed. The musky scent of Brody's cum hit Sam's sensitive nose casuing something feral inside of him to finally broke loose. He made one final thrust against his lover. His balls tensed, and Sam reached orgasm, shooting watery wolf cum out of his urethra and into Brody's ass.
The two werewolves collapsed into each other. Brody felt Sam's arms being wrapped around him and holding him tight. He let out a soft moan as Sam's still-knotted cock continued to spurt wolf cum deep inside of him.
Cuddling against his lover, Brody rumbled, "Rrrr... You know, Sam. I still haven't used my Dare from before?"
"Mmm?"
"You didn't respond when I used the curse to turn you gay. I can still Dare you."
"Mmmrrrr..." Sam grumbled. Having spent most of his energy fucking Sam, he drifted to sleep.
"For your dare Sam, I dare you to become my mate for life," Brody whispered, as he too fell asleep.