Since you asked...

So anyway. The previous post about Jacen and Vergere happened in books about 4 to 5 years ago. Jacen sort of apprenticed himself to Vergere and he learned to pull from the light and the dark side and questioned if there really was a seperation.

As it turns out Vergere died during that 20 book story arch (This amount of books was also created to sort of bring all of the writers to the same time line. For many years the books were all over the place and the time line was hard to follow). She was recently reveled to have been a Sith and what she was teaching to Jacen was a step toward the darkside.

Now in his 30s he learned the truth about Vergere and since he trusted and beleived in what he was tought by her, he was convinced to learn more about the Sith and started his path toward being a Sith Lord. He thought he would be able to control his power and like his Grandfather (Anakin Skywalker/ Darth Vader) bring piece to the Galaxy. Yhea, well He got the Dark Lord part down. In the recent story arc of 9 books he has become Darth Caedus. Along the way he has killed Luke's wife, Mara Jade, and tried to turn Luke's son Ben to the Darkside.

Wow, how nerdy of me :o)