A moment later, I felt the warm wetness of my spend spill into my shorts. There was something almost painful about it. Strained. The bliss overtook me. I felt my sister's hand on my head. Stroking my hair lovingly. I became very aware of sharing this intimate, vulnerable thing with my sister. It made everything more satisfying, yet also scarier.

When I got my strength back, I rolled off of Lucy.

"That was nice," she said, "Thank you for letting that happen."

"Did you...?"

"Not really," Lucy said.

"I'm sorry," I said, meaning it.

"No, don't be," Lucy said, "Honestly it was totally awesome. Different. I loved it."

I nodded,...