You are clearly not equipped to handle this. Ask for help.

"Okay... first, thank you for not trying to kill me."

Alina raises one eyebrow quizzically. It's really cute. You're not sure if it's the post orgasmic dopamine overload coursing through your veins but you think you might be catching feelings for the murderous, vengeful and yet completely subservient pet you just procured for yourself despite everything she just said. In fact, it's kind of hot in its own way.

"Of course sir. I am a part of you, everything I say and do is in service to you. I apologize for any distress my words may have caused, but it is critical that you understand the extent of your predicament, anything less would result in catastrophe. Would you like to fuck Fuckbunny some more so that you can use her holes to soothe yourself while you gather your thoughts?"

You look down at your pet, your deflated cock still plugging her cunt dripping with your cum and slowly pull your cock out, watching your seed drip out of her as you do so. You are entranced by the sight, but you shake your head and try to focus on the task at hand.

"That would be nice but right now I think I need to pick your brain on what I need to be doing."

Her cunt is pulsing, it's almost hypnotic. You need to... okay, just a little bit first. You have a whole year. You give in and rub your cockhead on Sexy Terry's cunt slick with your combined juices and pop your head back into her welcoming hole. She moans seductively as you do so, biting her lip again. Clearly she knows what you like, seeing as she can read your mind and all.

"Unggghh~ Gasp! Of course, Sir."

"So how do I do this? Is this like where we have a fuck-a-thon training montage? Are we doing a makeover?"
"No, sir. There is no conceivable way you can bring yourself up to the level of attractiveness, and capability that would be required for you to be even close to being in contention as a proper suitor. Not to mention you're still her brother and you've **** her once already. That ship has sailed."

Your spent cock having shrunk somewhat has an easier time gliding in and out of Alina's cunt now. You try to focus on the conversation at hand and not get too distracted by the delicious cunt wrapped around your member.

"Then what the hell am I supposed to do?"

"Lean into it. You're going to have to kidnap, isolate her and make her give up all hope, and hope Stockholm syndrome kicks in and gets you past the finish line."

"...That's really fucked up. She's my sister."

"You shouldn't have **** her then. And technically you've done it once already using magic to expedite the process. You just have to try it again, this time without the 'training wheels', so to speak."

"Okay, fair point. Where do we start?"

"We need a place to keep her isolated while we try to break her. The quest didn't specify that she specifically had to be submissive towards YOU, so I think I might have an idea. I have an ex with a sadistic streak that just so happens to live on the outskirts of town. No one would find her there, and knowing my ex, they're exactly the kind of person that would be into breaking someone like your sister. "

"... I don't know if I want some dude fucking my sister."

"Of course, you'd prefer to be the one **** her yourself, because your brotherly love for your sibling only extends so far. It's a woman, and a hot one at that, if that makes a difference."

The accurate assessment hurts more because you know it's true. The girl can read your mind after all. You really are a piece of shit. But what Alina just said opened up a whole another can of worms. One that needed immediate addressing.

"Wait, you're a lesbian?"
"No, I'm bisexual."

Hot. Fuck yeah.

"And she does a little escort work on the side, so as long as you manage to convince her that this whole thing is an elaborate roleplay session and pay her accordingly, she'll be able to provide the experience you will need to properly dominate your sister in the timeframe. And it'll also give you an opportunity to sample her services as well."

"Aren't escorts expensive? I don't have that kind of money."

"... Sir. You can stop time. You've watched Groundhog Day. Rob a bank, an armored truck, you could probably rob the US Treasury and get away with it. Money is the least of your problems right now."

"Oh, right."