Indeed, Aaron felt the change, or rather he felt the pain of his body reorganizing itself as he started to lose his humanity. His size increased by almost 2 feet, his body mass doubled as he gained very strong muscles; his clothes were destroyed in this process, but that wasn't Aaron's problem, who was perfectly fine being nude. He stood up, and casualy fliped over the SUV to demonstrate his new strength. Yellow fur began to cover his body as his face changed to become a lion's muzzle, his front teeth changed to fangs and his hair to a dark brown mane.
Helen stared and enjoyed the show: "Sorry, Kelly, you won't get a new sister: he's transforming into a strong, muscular, very male lion. Great ! Come on, Mr Lion, fuck me as you change !"
Helen got on all four and presented her wet pussy to Aaron's erected cock, who was more than happy to fuck her. Aaron's transformation continued as he gained a lion's tail and mental changes occured. Aaron's new personality was not human, nor male. Aaron begged, as their voice gained a few octave: "Don't ... call me... Mister ... anymore !"
Kelly smilled as she saw 6 additional nipples appearing on Aaron's torso and belly. 8 breasts expanded, Aaron's waist narrowed while their butt expanded. A pussy formed below their dick (which was shrinking inside Helen's vagina) and Kelly immediatly thrusted her lion tail inside her brother->sister's newly formed pussy. Aaron felt two orgasms at the same time: a small male orgasm as their penis delivered its load inside Helen, and a big female orgasm as Kelly's tail ravaged their pussy. Their shrinking dicks and balls, the last part that was still male/human moved inside their body and became a feline clitoris and ovaries: Aaron was both mentally and physically female, and she was happy.
Helen and Kelly admired their mate in all her glory. At 7'6'', the new lioness was slightly taller than Kelly and her boobs were only D-cup, but except that she was exactly like Kelly. Helen was a bit disapointed, but at least she had enjoyed Aaron's dick one last time. She briefly theorized that the animal transformation could be based on human genetic material, but Aaron and Kelly were fraternal twins, not identical twins, so they had not the same genetic material. At least before their transformation. Could the virus change franternal twins into identical twins ? Apparently, yes. It won't be the strangest thing this virus could do.
Kelly, on the other hand, was glad she got a sister who was exactly like her. Aaron and Kelly used to get along quite well, but that was nothing compared to their bound after their transformations. Kelly felt her sister was also a lesbian, and the two twins were attracted to each other as much as they were attracted to Helen the cheetah. For human beings, incest was an absolute taboo, but animal-hybrids did not have the same taboo. It was okay, for two lioness sisters, to be lovers.
The new lioness roared, informing all the animal-hybrids of this town that Aariel the lioness was joining them for the Great Hunt.
Kelly asked her sister: "So, Aariel, how do you feel ?"
"Hungry !" said Aariel as she wanted to share a meal with her two girlfriends.