Not long after the cat began to drink, a strange sensation went through its body. As if it suspected the pond's water, the cat stopped drinking and backed away from the pond, but it was far too late to stop the changes.
The cat's body quivered before it started growing in size. Soon it had grown to the size of a lynx, then a large dog, then a pony. The cat's body bulked in power as it grew. While it was still built for sneaking up on prey and ambushing it, it was now more built to take down larger prey. The tip of its tail darkened as the hairs on it grew longer, forming a distinctive tuft.
However, it was hardly becoming just a bigger cat. The cat's head was reshaping as it grew. Its skull expanded to make room for a growing brain, a brain that was filling up with knowledge. The cat's ears remained perched on top of its wider head, but they were losing their points as they became rounder. The fur on its head grew thinner, though darker hair was pushing out of its scalp. The new hair grew longer until it has flowing black locks. The fur on the rest of its head vanished, revealing bronzed skin. The whiskers also disappeared as the muzzle sank back into its face. The mouth flattened before pushing out two plump lips, though the nose remained mostly flat and close to the mouth. The eyes remained largely the same, but changed size and shape as features softened and redefined. When the head was finished, it resembled a human woman's with round, furred ears, cat's eyes, and a nearly-catlike nose.
If there was any doubt to the former cat's sex, the changes to her chest put that to rest. Her uppermost pair of nipples moved further upward onto her chest. She gave a gasp as the flesh surrounding those nipples started swelling out. The fur leading down her neck to her chest thinned out as her nipples expanded out on inflating orbs. Her altered mammary glands grew more sensitive as they grew out to a respectable size. The fur finished thinning out, revealing more bronzed skin that left her large breasts bare.
Then the biggest change started happening. Up until now, there were only alterations to what were already there. But now something new was forming. The shoulders tensed before pushing out thin nubs. The nubs grew longer and longer, a joint forming in the middle. The extensions were bald at first before they developed a fine down. Then long feathers grew out to proper flying length. Muscles in the back and the new wings strengthened until they were capable of taking flight.
Now what had once been a stray cat stood a majestic sphinx. She was a classic sphinx with the body of a lioness, the wings of an eagle, and the head and breasts of a woman. The woman part of her was not hideous to behold, despite some of the remaining feline features. Indeed, her catlike face and lioness ears gave her an exotic look. Her long dark hair trailed down to mostly cover her full breasts.
The sphinx gazed down at her reflection in the pool with some marvel. Her mind had expanded exponentially from the simple cat she was before. She was as smart as any human. Smarter than most, really. For like any respectable sphinx, her brain was largely devoted to the creating and solving of riddles. And a mind as clever as that was also capable of self-reflection. It was plain to see that the pond was responsible for her evolution. She was certainly far more than she was before.
But what did she want? She may be a higher being, but she was still a predator. She could bring down much larger prey with her bigger body. But why should she hunt simple animals? She was a sphinx after all. She could set herself up at an important road and challenge travelers to answer her riddles. Being of such a superior mind, she could make several meals of the simpler humans who couldn't figure out her riddles. But did she really want to limit her mind to being a predator? Was her thirst for knowledge stronger than her thirst for blood? There were cities where she could learn so many new things if people were not frightened of her majestic form. Or perhaps she should take another drink from the pond and see how much more she could change.