The tigress sniffs the air in your general direction as she moves closer to you. The scent of her is practically overpowering. It's a strange, unfamiliar scent, not something you'd ordinarily consider pleasant either. Still you can't stop yourself from wanting to smell more of it. It's something you get ample opportunity to do as she comes close enough to touch her nose to yours before circling around you and rubbing up against your side. You realize that she's ready to mate, but what somewhat frightens you is that it's not so much a logical decision made from observing her behavior as it is an instinctual decision. In short, you didn't figure out that she's in heat, you just know.
She walks a little bit away from you but stops, her backside pointed towards you. You know exactly what you're supposed to do and spend a moment trying to resist the urge before realizing that you simply don't want to. You're a tiger, after all, and she's a tigress. What's there to think about? You're atop her in short order.
As you sink your self deep within the tigress you realize your mistake...if that indeed is the right word. Your human grasp on language and logical thinking drains with every moment you spend indulging your animal instinct. Your human mind slips away and everything you know is forgotten as you mate with her. But the time you release the old you is gone.
A little less than an hour later as you and your mate rest against each other for warmth, you're dimly aware of a human standing over you. She smiles and speaks to you, but her words are meaningless to you, so you ignore them and close your eyes again. Something about her tells your new instincts that she's not to be trifled with.