Robert changed and grew, to put it shortly he became a larger Male version of Mary.
Mary gazes at his new form and feels her sex start to leak fluids all over," Now, let us mate in perfect union!", she screams.
Robert inserts his cock into her over sized pussy and begins to rock back and forth, both of them moaning in unison, suddenly he feels his new cock pushing adapted sperm into Marys Womb to be fertilised.
Soon after half an hour of sex Mary started panting hard and loudly as her stomach expanded greatly.
She ran her clawed hands over her expanding belly. Her pregnancy was shortlived however--labor came within minutes.
She growled and squatted as copious amounts of slime poured from her cunt, digging her claws into the ground.