Cherry English "Step-Sisterly Thing To Do"

You're feeling particularly brave and horny today. The shower in your step sisters ensuite is broken, so she's needing to use yours, but you boldly ask if you can watch her shower. What a creepy perverted step brother you're being, but you have no shame and want this opportunity to have some fun with your sweet sister who you've always fancied. You won't leave her be, so she gives up and allows you to touch yourself. Suppose it's the sisterly thing to do, right?