Bryan thought about Katy, his girlfriend, who would be at his house at 7:00h if she'd gotten his mobile message. Thinking about her aroused him... or was it the slight touch of Mark's fingers as he'd touched his furry sheat?
Mark's heart started to increase it's beating rate. This coul'nt be true. He'd lain in bed many nights, phantasizing about dogs and what nice stuff could be done with them. He'd often dreamed about touching a dog's sheat, rubbing the red, slick cock out of it's home and then... he started to get horny and his own cock hardened itself.
Bryan, whose nose got better and better by the minute as his own transformation creeped onward, got a whiff of Mark's arousal. It was a strong, musky, very maskuline smell and it filled Bryan's head very fast. All thoughts about his girlfriend Katy wery put aside as his doggy mind focussed on this new, wonderful scent.
Mark's penis was getting so hard he had to put his hands inside his pants to move it into a more pleasing position as his underpants obstructed it way too much. Touching his member made im gasp slightly.
Bryan observed the hands of his friend as they traveled into his neither region and his doggy mind decided to give Mark a helping hand.
"Wait...grrrwufff..." he growled and got to his knees. The tip of his doggy cock slowly grew out of his still exposed sheat.
Mark eyed his friend as he got to his knees, opening his trousers' fly with agile hands (which were sprouting a fine coat of black fur by the way).
Bryan dropped the pants and underpants to the floor, so that Mark was naked on his bottom half a moment later.
The cold air of the room hit Mark's hard dick which proudly jutted it's tip up to the roof. His member was of bigger-than-average size and a small drip of pre-cum glistened on it's tip.
Bryan smiled and felt his own cock slithering out of it's sheat some more. Mark's erogenous scents were arousing him more and more by the minute. He felt that the doggy infection had also taken hold in the body of Mark and that some sexual stimulation was needed to make his human friend a new member of the black shepard pack. His family, which was still roaming it's house, would be proud of their son and newest meber of the pack if he'd infected Mark to join their ranks. And then Katy would be next... oooh, sweet arousal.
Mark thought about all those nights of dreaming about sex and dogs and sheats and fur and saw a very animalistic shimmer in Bryan's eyes. His friend was turning into a dog and the arousal that started to fill this room fastened up the transformation. His friends ears were already growing pointed and fur was spreading all over his body.
Unbelievably this turned Mark on much more than would he have ever thought possible... would he be shapeshifted too if he'd give in to his new sexual urges?
Bryan's head moved closer to his friend's hard dick and his nose inhalated it's musky scents. His doggy cock grew to his nearly full lenght and his mouth opened slightly. He was panting and his vision got blurry.
A short second later his mouth opened more and he took a full mouth of Mark's hard cock.
Unbelievable scents and tastes exploded in Bryan's mouth and his tail started to wag uncontrollably. His tounge lapped across his friend's cockhead and his head made sucking movements to lubricate the cock on it's full lenght.
Mark's head exploded in a wave of sexual delights as his transforming friend Bryan started to suck his hard dick. For a second he whimpered doglike, then he moaned. The sucking sensation that radiated from hos groin was the greatest thing he ever experienced in his young life.
Bryan sped up his sucking motions, his furred hands stroking Mark's legs and tights. His mind was taken away from the sexual urges and his friend's scents only helped blocking out the last vestiges of his once human mind.
His own dick had grown out of it's sheat proudly and he felt that it was neccessary to put it to use soon as it was sending it's own feelings of sexual tense throughout his aroused body.
Mark felt a orgasm comming way too fast and eyed his shapechanging friend kneeling and sucking in front of him. His back was nearly covered in dense black fur now and the transformation did not seem to slow down either as his legs were cracked into a new, doggy-like shape in the whim of a second. His friend turned into a full-blown dog while he was sucking him!
Bryan's face pushed into a elongated muzzle, but he did not stop sucking Mark. The erotic scents of his friend's dick exploded into his mind once more as hot, slick human semen started to jizz into his doggy throat. He gulped it all down, finishing his transformation into a dog at the same time.
Mark could not believe that he was just cock-sucked by a great black german shepard, but the release had felt so good he stopped to care. His human thoughts were slowly extinguished by new, better doggy mindpatterns.
Slowly he removed his hard dick from Bryan's muzzle. It was still covered in sperm and saliva, but Bryan lapped it clean as soon as he was able to.
Than Mark spotted the proud doggy cock of Bryan and he immediately knew what he had to do...