Kelly was drunkenly sniffing and inspecting Casey’s lower abdomen when a smell hit Casey’s nose like a wall of bricks. It was wild, but soft, musky, but sweet… it was coming from Kelly. Casey lowered himself to inspect Kelly, landing on his forepaws similarly to a dog to find the source of the smell. As he got closer, his body burned all over with feral impulses. He didn’t realize he now balanced with a thick, muscular tail like the other Roos. The smell was stronger as he got closer to Kelly’s tail area, and he licked her lower back between huffs and sniffs. Kelly lifted her tail slightly, trying to help her friend, watching with stupor, her head craning over her shoulder. Casey saw thick, silvery trails cascading from under Kelly’s tail and was hit with a blast of pheromones as he lost control, leaning in to huff deeply and lick the slimy substance. This was so much better than the milk! He lapped it up more, his changed face giving him easier access to the source of the substance. Kelly jolted, not expecting the contact, but involuntarily raising her tail higher in the process. Squirts of the juices spurted out at Casey’s contact as he began to feel a pressure building. Instinctively, he lifted himself up, lining up his lower abdomen with the underside of Kelly’s tail. He felt a cool breeze as the red tip of his transformed equipment peaked from a hole in his lower abdomen. He began slowly inching forward, searching for his target but not sure of his actions, only doing what felt right… what his instincts told him to do. He embraced Kelly from behind, clawed hands grasping her muscular hips. That’s when his searching tip found warmth, and he inched forward towards the warmth until his length was surrounded by Kelly’s slick kangaroo sex. Kelly’s mouth was agape, drool hanging from her plush lips. Casey towered over her now, and completely overpowered her. But she felt oddly safe, and trusted in whatever was happening, though neither were in control. Casey finally reached the base of his new equipment and could no longer travel forward into Kelly’s love tunnel. Giving in to his newfound animal instincts, he began to pull out and thrust back in erratically as his ears grew larger. His assault on Kelly continued as he started to find a rhythm. Half-human Kelly was lost to pleasure and moaned as she was railed by the almost fully male kangaroo Casey, her human face twisted in intense pleasure. Red fur coated Casey’s body, the last of his changes taking effect as he felt an intense swelling. He was losing his mind as Kelly’s muscles contracted and squeezed his equipment. He caressed Kelly’s somewhat human curvature, feeling her soft girlish skin with his changed paws. This sent him over the edge as he plunged as deep as possible, wanting to make Kelly a mother again, this time the way he wanted. He felt something tight kissing the tip of his penis, not knowing he had entered her womb, and shot his load into his former baby-sitter, arms wrapped tight in an embrace around Kelly, his soft fur tickling her back. Both were lost in orgasm as the Casey felt his final spasms, having sealed the deed.