Tiff then slowly approached Katie and once she was close enough to Katie she felt her hair.
Katie was confused by this action and in the midst of her screaming stopped to sniffle
"Tif-f-f... *sniffle* is it still you in control?"
Her questioning quickly turned to screaming again when Tiff reached her shirt and ripped it off, "OH MY GOD, TIFF IS RAPING ME, HELP-" Katie's screaming was cut off as Tiff pushed her enormous hairy tits against Katie and muffled her. With her left hand she reached for the Formula-R and tried to pour it into Katie's mouth. "Pbltt!" Katie forcefully spat.
Getting fed up Tiff drank some more of Formula-R but didn't swallow. Instead she kissed Katie and pushed the liquid into her, forcing her to swallow. Now Tiff backed up to see the magic commence.
Katie, sobbing from the experience, curled up into a corner as she felt a pain in her stomach. Suddenly hair covered her body much to Tiffs pleasure as she moaned and fingered herself. "OH MY GOD!" Katie exclaimed as her frame grew larger to the point of shredding her clothing leaving her harry and naked. Then, as Tiff was climaxing in her masturbation, Katie's muscles and intelligence came in. All of a sudden Katie began to stop groaning and began moaning as she felt her whole body get muscular leaving her akin to a hybrid of a gorilla and human.
Katie, when she looked up, had a unibrow and facial features akin to Tiffs, but most important of all, she had the same lust for pleasure Tiff did.