Make yourself worthy of her

Even though you're in the middle of a power fantasy, you do realize it's not exactly fair that you turned your sister into your perfect wet dream and had her fall in love with a guy so different from her own tastes. Your wishes may have retroactive effect, but you still remember Sam always had a type when it came to men which you don't at all fit into. Tall, muscular, outgoing. You may have erased all of her former relationships from reality, but you still see the guys in your memories and you have to say... You wouldn't mind looking like them. You always envied them for their bodies, maybe in big part because you knew it was the perfect pussy magnet for your crush -your own big sister- and it would probably please her.

"I wish I did look exactly like what was the perfect fantasy for Sam before I changed her mind with my wishes. I wish it was still the perfect match for her."

You feel a little dizzy for a moment before realizing the floor now seems further away. You look at yourself and touch your arms and torso in amazement. You now may be 6.3 ft tall, with a football player's musculature and a californian surfer's tanning. Your shoulder's lenghth may have doubled, and you realize one of them is covered with some sort of polynesian tattoo. Which leads you to the fact that you're shirtless and there's no hint the piece of clothing you were wearing a few seconds ago ever covered you. Did your wish also made it so you would dress -or undress- like one of your sister's fantasies? Well, you don't really mind...

"Oh my!" Sam suddenly exclaim in marvelment as she pulls your dick from your boxers and you discover how much she had a fetish for giant cocks. This monster seems to be one entire foot long and highly impractical, but your older sister smiles in amazement and starts licking its whole lenghth. It obviously suits her taste, but you can't help but be worried by how unpleasant it may be for her when it'll come to actual sex. It's probably literally more than she can chew on. "I wish all of Sam's holes would be supernaturally flexible so my dick could magically fit entirely in her without ever hurting her or stretching her permanently and it would still feel tight and good inside of her. I wish she would be so turned on by the taste and smell of my dick and cum that she couldn't suck on me without touching herself."

As she put your glans between her lips and start gobling it up, she lets out a moan and slip a hand under her skirt while the other one starts wanking you vigorously.