There are a lot of stories to choose from in this subcategory. I decided to try my hand at this type of story last spring, from two different angles.
One was an 8-part, "slow-burn" series, where the action between mom and son ratchets up in each chapter. I wanted to write something that didn't get mom and son in the sack together too quickly.
I've completed 6 chapters and will finish the last two before December:
The other was a standalone, 2 1/2 Lit page story that was a variation of the mom-and-son-on-a-seat-together theme:
The latter story did quite well and currently is the most-viewed story on Literotica that's been published since May 1 of this year. Since it did well I decided to write a sequel to it, but the story stands on its own.
It's interesting how powerful and popular this theme is.