The first thing the two of them felt was their hearing going fuzzy, as if someone was shoving earplugs into their ears. Indeed, both boys' ears were folding back into the sides of their heads and disappearing. When they're gone completely, Pat and Jack can't hear anything. Pat pressed his hands to the side of his head, but couldn't feel anything. He clapped his hands right next to where he figures his ears should be. He heard nothing. The two soon-to-be former humans then feel a pressure in two spots on top of their heads, and after a couple of seconds they can hear again, and it's a lot clearer than before. Jack reaches up to one of the pressure points and feels a furry, triangular ear. He shudders, the feeling being incredibly more pleasurable than he expected.
Next, their eyes start to itch as they grow bigger and rounder, Pat's just gaining slitted pupils and Jack's full-on changing color and gaining slitted pupils as well. Next, Jack felt a pressure at the base of his spine as his new tail pushed its way out, making him wince. Then, the boys felt exceptionally odd and uncomfortable as their hands and feet changed to become more paw-like, gaining retractable claws and changing shape to look a lot more like a cat's paws. Finally, memories consistent with the new reality come rushing into both their minds. Their minds try and reconcile those memories with their current ones, but it's too much for them, and they pass out, collapsing to the floor...
When the two best friends and occasional lovers next come to, they have splitting headaches. Jack got up on his hands and knees, rubbing his head all the while. "Ow..." he said, wincing as he keeps rubbing his head. He looks over at Patrick. "Did we knock heads or something?" the newly-minted Neko asked, his voice deeper and smoother than it had been in his previous form. "I don't know," Pat said, rising to a sitting position, rubbing the back of his head, "but it's certainly a possibility." The corner of Jack's mouth twitched a slight bit as he moved over to his best friend. "Well," he said, "if it's my fault, I'm sorry." Jack kissed the top of Pat's forehead. Pat chuckled at that and said "you kiss it better." A sly smile crossed Jack's face as he purred and said, the innocent twinkle in his large eyes disappearing, "that's not the only thing I'm better at...." A similar sly grin appeared on Pat's face as his tail swished back and forth and then curled in anticipation. "Be my guest."