Fuck her smart-ass.

You need her mouth free but you don't want to stop **** your little sister, so you decide to do the next best thing.

You think about how exactly you're going to go about this without your sister being able to escape, you realize that if you expand your timeslip field to encompass her body without including her four limbs, she won't be able to move but you can still make her feel every inch of your cock as you push it into her bowels.

You decide to test your theory and shape the field, expanding it slowly with your cock still buried in your little sister's throat.
Your sister starts to thrash more as sensation starts to return to her body below her neckline, but without the use of her limbs it's little more than helpless wriggling that only serves to enhance the mouth **** you're currently inflicting on her.

"MMmmpph!!!"

"Just so you know, if it isn't obvious already, Vanessa, I can stop time. There's no one coming to save you. The only people in the world that are moving right now are you and me. Or more accurately, me, and your body that I'm using as my new personal cocksleeve. You can scream all you want. In fact, I want you to fight and struggle and scream, it only makes this that much more satisfying for me. "

[Quest progress: Tutorial Quest #2: Vanessa Martinez submission score: 12]

"GGGGRRRRRKK!!"

"No one is coming to help you. The only person in the world that can end this is me. I own you now. I own you, I own your smart little mouth, I own your smart little ass, and I'm going to show you right now exactly what I mean."

[Quest progress: Tutorial Quest #2: Vanessa Martinez submission score: 14]

You slowly extract your cock from Vanessa's throat and watch her gasp for air with satisfaction. Your cock is slick with throat slime and you know exactly what you're going to use it for. You push your little sister down until she's on her hands and knees and reposition yourself behind her, pulling off her clothes to reveal her plump little bottom that you used to admire discreetly when you still lived at home.

It's exactly as beautiful as you remember it being. Vanessa is mumbling and whispering, seemingly talking to herself now, half out of her wits thanks to the extended facefuck you inflicted on her as you line up your cock with her tiny pink puckered asshole.
You savor the sight before you, your little sister Vanessa bent over on her knees with her perfect, tight ass presented before your cock, you rub your cockhead around her anal ring as your little sister starts squealing in panic.

"Please, Uly... don't do this. I'm your little sister. You can't do this to me."
"Really, Vanessa? The way you've treated me the past few years you'd think you never saw me as a brother."

Anger flares in her eyes as she looks back at you, her well fucked mouth set in a familiar sneer as she angrily whispers through gritted teeth.

"Because you were a creepy asshole that liked to peep on your teenage sister, you sick fuck!"
"Oh yeah. I know. That's why I'm doing this to you now, now relax, little sister. Your older brother has a present for you."

With that you push forward and start to push your cockhead into her impossibly tight anus as your panicked sister wriggles and flails under you trying to stop you from violating her further.
Your sister's screaming is music to your ears as the head of your cock slowly pierces through the resistance of your little sister's tiny little anus. Then her little butthole gives. You feel your cockhead slip inside her ass as her anal ring stretches to accommodate you.

"No.. no, no, no, noo-- AaAaaaaggghghh!!!!"

You start thrusting into her ass, buried balls deep inside her guts, grinding your cock into her to make sure she understands who she belongs to now.
You look down at your little sister screaming her head off while you sit on top of her, balls deep in her quivering rectum with your balls resting on her shiny ass slick with perspiration.

"You're fucking me, you're fucking my ass, oh god no, stop... Uly... please!"

"Shhhh- That's a good girl. This smart-ass is mine now."

In that perfect moment of sibling intimacy something unexpected happens. A box of white text flashes before your eyes.

[Time slip limit (Psy Power lvl:1) approaching. Time watch will power down in-]
[10...]
[9...]

You look down at the watch in panic. You're fucked. Of course you were too stupid to test the fucking thing first before leading with your dick and **** your sister. Your 15 minutes of fame is about to turn into 15 years in prison.