>>11279903
Granted! You are now conjoined with your twinnish sister, fused at the spine, specifically like two people standing back-to-back with each other. This arrangement would already allow you two to get sandwiched between two partners - boys or girls, depending on your preference... Your sister doesn't mind, she's bisexual anyway, and she loves to sleep around with many different people.

You might have noticed that I said "twinnish". This because you are genetically twins, but physically VERY different. Her biology basically takes the lion's share of any nutrients you two intake. As a result, she has an amazon-like physique, tall and fit; while you basically look like a petite nerd. Ironically, this helps you two get plenty of friends-with-benefits, because you can more easily attract those who love lithe girls and your sister can deal with people who love buff women; then, afterwards, you can convince your new partner to open up the relationship for a threesome. Which, admittedly, isn't that much of a stretch, given your condition.

You probably have already guessed by now, but your sister is considerably more dominant than you - which is to be expected, since her size and strength allow her to carry you around easily as if you were an empty backpack. Not only that, but your shared body is surprisingly flexible (which helps a LOT during sex); with just a bit of contortionism, she can easily fondle, grope and masturbate you all she wants. And she will do so, as a form of playfully bullying her "little sis".

>I wish for fluffy tentacles.