For Izzy, it was about the first time in this attempt that she felt like Riker actually might succeed. It had all been so wonderful, but wasn't going to make her cum. The steady vibrations on her clit both felt good, and were a sufficiently constant stimulation that they might get her there.

"Hey, Ri?"

"Hm?"

"What about... what about if you put a finger in me?"

Riker stopped licking, looked at Izzy for a moment, then nodded. He was far more delicate than he needed to be as he slowly inserted a finger inside his twin sister.

It was good, but it wasn't what she wanted. Izzy realized that...