3-2-1 Go!

In the back of his mind, Chase was surprised at the transformation. As his dick was hugged by hot human flesh he marvelled at how Alex had changed. Gone was the cute but serious partner he'd come to expect. Replaced with a cock-hungry doppelganger; a horny submissive slut begging to be ploughed. Even their usual lovemaking retained an air of normalcy -- however steamy it got it did not compare to what was happening right now. Alex was his toy. His plaything. A gibbering man-whore. And he belonged to Chase...

Grunting, Chase started to pump his cock in-and-out of Alex's rear. Working up to a steady rhythm, the canine topped his boyfriend, effortlessly bucking his hips as if he'd never tire. The mewling sounds from Alex translated perfectly to his ears: 'harder', 'faster', 'more'. He made no speech himself -- too exhausted for words. Probably too feral to maintain a simple conversation. His existence had reduced to pure instinct, pure pleasure. The rocking of his mammoth hips. The reciprocal bounce of Alex's fatty rear to his onslaught. The shallow breathing as he fucked his beloved...

Chase rode him hard. His cock plunged repeated into Alex. Exploring his depths. Cataloguing every contour, every bump, every feature of his inner walls. Mapping his insides and navigating through fiery touch alone. Pre-cum glistened around his lover's ring, dripping as it was expelled from between their mingling flesh as he pounded Alex. The wet slap of ass cheek, the swing of his heavy balls -- laden with life-giving seed -- as they struck Alex's butt...music to his ears. Alex's own jewels, his human pride, flopped back-and-forth, his smaller erection dangling over empty ground, but no less potent. The slam of beast against man echoed throughout the forest.

"GRRRR!!!"

"Eaahhh!!!"

Their vocalisations were incoherent; the pair caught in a blissful rut.

Chase held Alex tight as he rode. Hips bucking. Thrusting. Slamming his huge cock through the gates of heaven on earth. Kissing the depths of his lover. Growling, snarling, hissing as he strove to go deeper. Alex hugging his broad arms as they wrapped around his chest. Clinging to them for dear life as if he'd fall forever if he let go. The forest around them shivered in tune with the wind and their pleasure. Rustling green canopies providing the perfect backdrop for the animal mating. Slobbering, slaving, biting...Chase made sure he was being careful with Alex -- he knew how frail little humans could be -- but kept his sensual assault as barbaric as possible. To extract maximum pleasure from their fuck. With each movement, he knew Alex was all for it. The human pressed his ass against his groin, trying to push him deeper, to scratch an itch that was just out of reach...

This was enough to send Chase over the edge.

"GGRRRRAAAAGGGHHHH!!!"

His roar shattered the serenity of the forest. Birds flew from trees. The mountains carried his proclamation of conquest far and wide. He could take no more. He'd held back the torrent as best he could, but...rubbing against those soft insides...nice, warm flesh caressing his aching shaft...it all caught up to him. Chase held Alex close as he erupted. Jets of seed surged through his manhood, his essence launched into his human lover. Thick waves of cum blasted into Alex. Enough to sire many litters of pups had his lover's sex been different. Rope after rope after rope. Emptying his cavernous balls into his prey. Feeling the flood of semen push back against his cock, finding no more room in Alex's guts. The hot tsunami squeezed past his cock and spilled outwards, matting some of his fur around his sheath. He hadn't managed to insert his bulbous knot into the human, knowing it would probably be too much for his boyfreind to handle. Without that tightest of seals, lots of his seed escaped.

After a minute of Chase bucking against his ass, Alex triggered his own orgasm with a swift tug of his erection, his prostate doing the rest of the work. His pitiful load by comparison spilled onto the ground, demonstrating to his lover that Chase was the real male of the pair. A harmless insinuation in their subconscious; one they knew not to abuse and treat as it was: a sexy fantasy.

Feeling bloated by the volume cast by Chase into his bowels, Alex strained as he adjusted his position. The two lovers righted themselves, Chase sitting while Alex rested atop him. Gasping. Panting. Sucking as much air in to compensate for the intense exercise. Chase's body rocked and tossed him around, still bucking involuntarily. Cock buried deep in his ass. Embraced by his tender insides. The bulb of his knot right at the entrance, a large enough mass protruding from Chase's sheath for Alex to sit upon without sliding down any further.

They remained like this for several minutes, climbing down form their orgasms. Then, Chase lowered Alex gently to his side, resting him on the forest floor. An arm extended 'round his waist, and he held his lover tenderly.

In the afterglow, they cuddled.

It took a while before they could form words again, but when they did Chase's first instinct was to check his lover was okay:

"I didn't hurt you, did I?"

The soft rumbling depth of his voice soothed Alex, who snuggled against the big furry lump. His heart warmed by the tenderness Chase exhibited -- the small pats and strokes, the gentle easing out of his cock from Alex's ass. A pleasant sigh escaped him as he lay there.

"Nah, you're good."

Another minute passed in silence. Their bodies wracked with exhaustion. Both knew they should get and leave soon, lest someone stumble across the sexy scene. They waited, however, to gather their strength. And enjoy the moment...

"Hey," said Chase, whispering inches from Alex's ear.

"Yeah?"

"Sorry about your clothes...I wasn't thinking..."

Alex looked at the destruction wrought upon his outfit, and just smiled.

"No big deal man, I brought spares in my bag."

He sensed Chase exhale and relax, and it filled him with happiness. His boyfriend's loving attention was welcome, and he thought about how he could repay him for giving the big dog such a roll in the hay. It had been his idea to come up on the trail, find a secluded place, and role-play this hunt. But as they rested together, bodies intertwined, he realised how much joy it had brought Chase to let off steam in a way he never expected to do: letting his instincts take over. He knew exactly what to dangle in front of his partner:

"So...d'you wanna do this again sometime?"

He heard Chase gulp, as if he'd been nervously working up the courage to ask the same question. He chuckled, and turned part-way to face his lover, stroking his furred muzzle with his hand.

Chase licked his lips and smiled. "Yeah, I do. That was fun."

"Then it's agreed. We'll do this again."

"Looking forward to it."

Alex received a big lick from Chase -- his face once again drenched in his lover's moisture. The canine anthro gave a warm grumble. "I love you," he said, his deep voice resonating with appreciation.

"I love you too."