Jump her!

Then, a crazy thought comes into your mind. Can you take Sia down? If you do nothing, she's bound to find you, and running just seems ridiculous, so why not try and get the upper hand here. If anything, you got the jump on her. She doesn't know that you're here, so you can easily take her by surprise. The more you think about it, the more plausible it seems. Well, might at least make this exciting for the research team...

You poke your head out from over the backrest and see that Sia's definitely still there, looking for you. You can't see what way she's facing, but you'll try your best to take her down no matter what. You stealthily undo your zipper, so that your cock is ready to go, no matter what. You grab on to the backrest and take a starting position to jump Sia. With a swift jump, you leap over the backrest and push Sia to the ground. You definitely feel her tits in your hands, meaning she was facing you. She lets out a startled scream as you both topple down. Once you land, her torso and arms are on the floor, but her ass rests on the couch, making her lower half and her cock dangle over her head. You sit on your knees on the couch with her legs in your hands and look over her. Since you have her where you want her, you waste no time in claiming your prize.

Sia manages to blurt out "Hey, what's the big idea? Are you ou-AAH!" before you penetrate her asshole with your finger.

You're kinda glad you managed to find it so easily. You start fingering her ass while rubbing your cock with your other hand. The rush of adrenaline lets you quickly get a full erection.

"Yeah, that's right! I'm in charge now!" You say and chuck a wad of spit around Sia's asshole so that you lube her up as best you can.

With one motion, you quickly pull out your finger and stick your cock in between her cheeks, plugging her ass before she has a chance to react. Another yelp comes from Sia's general direction as you feel her sphincter tighten around your dick.

You snicker "Heh, for an agile girl, you sure have one tight ass."

It's hard, but you manage to slide your 6-inch pecker inside her unbelievably tight anus. She lets out more screams as you do. It definitely feels amazing, so you can't wait to start fucking her. The sudden rush of confidence helps a lot as well.

You haul her legs over your shoulders and start going to town on her ass. You pump in and out, smacking hips with the girl that almost had her way with you. The hunter has truly become the hunted. With every thrust, Sia lets out a moan under her breath.

You say "What's the matter, not so tough now are we?".

She replies with a shaky voice "Sh..shut up! I've never been... NGHHAA!"

You cut her off by thrusting balls deep inside her. You were definitely expecting some resistance from her, but at the moment, she seems unwilling to even try. Her confidence and strength seem to have been replaced by submissiveness. You don't take your situation for granted and enjoy Sia as best you can. You start thrusting inside of her ass faster and faster. Once you feel her ass getting rough, you spit a wad of saliva down there to oil the gears back up.

You get an idea and say "Here, you might like this..."

You reach your hand around to Sia's cock and start stroking it, just to give her more enjoyment out of the situation. Sia immediately starts moaning louder, giving you a rush of hornyness that lets you pound her harder and faster all while jerking her off. Sia's cock feels hot and you can feel it throbbing in your hand. Stroking up and down her 12 inches is actually quite a workout. You can't even manage to fit your whole hand around her shaft. You go from right hand to left hand to both hands, stroking her junk while pounding her extremely tight ass at the same time.

You feel as time flies as you take your dominance over Sia, pounding her tight hole with all of your might, all while rubbing her giant cock with your hands. Now and then, you move your hand over to her tip, which is constantly dripping precum all over her, and use it as more lube. It's quite slippery and works much better than your spit. After a while, you start feeling pressure building up inside you, more specifically in your dick. Sia's cock also gets hotter and slightly bigger in your hands as you start stroking it more and more. Both of your orgasms are building up. You feel amazing, so you start giving Sia's asshole all you've got, pounding her hole with incredible speed and ****. She starts moaning and breathing heavily, feeling her balls preparing a giant load of cum. As you keep thrusting and stroking her meat, you feel it start twitching and tensing up. Your own pelvis starts going in autopilot, thrashing inside of her. You feel your mind go hazy and you finally cum. you spray a giant load straight down her tight asshole, recoiling your head in the pleasure. You quickly get back to your senses and finish off Sia as well. You start stroking her shaft as fast as you can, aiming it around where her face is. You feel it twitch and shoot out a massive rope of jizz all over her face. She starts moaning loudly, as her ropes of cum fall inside her open mouth. After a few big loads of sperm, Sia starts **** on her own cum as she can't swallow it as fast as she's spraying it out.

After a while, her orgasm also subsides and you pop your cock out of her ass, taking a seat on the couch. A second later, the lights beam on and the room is filled with light. As your eyes adjust to the brightness, you take in the scene before you. Sia's laid out on the floor, with her entire face covered in sperm. Her cock is still leaking some on her body and on her tits. Her eyes are closed, but she's still breathing.

"Guess she's just taking a nap."

As you think that, the speakers switch on and Alan speaks up, "Well well well, props to you. We didn't think you were that brave and stupid to try and take on Sia, but I guess it worked out. That's something we definitely didn't expect! But hey, that's what the tests are all about. I guess that means we should improve upon the shadow model's ability to TAKE cock as much as they like to dish it out. All around, useful test, but it's time to get back to your room. We'll grab Sia too when she wakes up."

You pick yourself up from the couch, feeling pretty proud of yourself, and stride over to your room door.

You got the "Hunter" ending with Sia.