Never Know

After about a minute of simultaneous orgasm during which neither of the twins was particularly conscious of their surroundings, they both came back to earth, slowly, together.

It was done. Liam kept his now softening cock inside his sister's pussy for a long time. He showered her face and lips with kisses. They kissed passionately, entwined in each other's bodies. It felt right at the time.

Then, finally, he pulled out, and his cum came rushing out of her.

"Oh god," she said, "it's a lot."

She had nothing to compare it to, but it was, in fact, a lot. When their father had told them to clean up any mess before the parents got back, even the twins hadn't anticipated what kind of mess they'd be cleaning up.

Liam and Emma both received a huge confidence boost that day. They continued to lick and suck and fuck each other for the rest of their lives, in the short term frequently, as they got older less frequently, on special occasions.

No-one would ever know about their illicit affair, not even the people they ended up marrying. As they got older, they kept an unspoken understanding, between them, that fucking each other wasn't cheating. It was the only exception.

They went off to different universities, but they did so confident in their lovemaking ability, and confident in the knowledge that, if ever either were going through a dry patch, or otherwise just needed some loving, it was only ever a train ride away.