Tenel Ka was Jacen's long-time pal. They met at Uncle Luke's Jedi Academy where their friendship grew over time. In a nasty lightsaber training accident (TK's fault D:), Jacen sliced off Tenel Ka's arm. He's always held that guilt inside of him and he always blamed himself for it -- even though she always told him it was her fault.

The cute little semi-couple in the YJK series and a who-the-hell-knows in the NJO, left people wondering just where Tenel Ka would end up in Jacen's life at the end of the NJO and beyond. Parts in the series showed that TK cared for Jacen more than even Jaina could imagine (and I'm sure she can imagine quite a bit), but did Jacen care for her the same way?

The Joiner King came along and gave us a meaty chapter full of Jacen and Tenel Ka. He goes to visit her to ask for a fleet/help with the galactic problem at hand -- and he ends up staying the night. People say that they were using each other (him to get the fleet, her to make her suitors jealous) -- but the people who've read the YJK and know the background of these two say that "they always banter like that" and "they would never use each other like that, especially because of the way they feel about each other" ... so then there was that debate. There was also the debate of who was going to have the rumored baby in the Dark Nest trilogy. A lot of signs pointed to Miss Tenel Ka -- after the fact that Jacen spent the night with her and Han's mention of how Jacen was "good with kids"...

Those debates were put to rest once the Dark Nest Trilogy was fully released. Tenel Ka had a baby and right after Jacen was introduced to the kid (who didn't have a name until the next series), the new parents had to fight off an attempt on her life (thank Ta'a Chume). Now, into Legacy of the Force territory, the child is still alive and kicking, her name is Allana and she has her mommy's looks. Awww, Jacen has a little spawn. Jacen was traveling on a pretty fine line for awhile, with Lumiya telling him he needed to sacrifice what he loves most to become a full Sith and save the galaxy.

He takes his new name after killing Mara Jade Skywalker and later, once Tenel Ka finally takes Hapes off of the Galactic Alliance's side, Jacen -- now Caedus -- realizes that Allana is the only person left who still loves him. And he would kill anyone who gets in the way of them, even Tenel Ka.

By the end of the series, once he's too far removed from his smarts, Caedus and his twin sister, Jaina, have a good couple of fights. No one bothers to try and redeem him and as his sister is in the middle of fatally stabbing him, he calls out through the Force to Tenel Ka to warn her of the approaching dangers they'll be facing. In the end, Jacen got his last har har and called out to Tenel Ka, cause you know, he cared about family, unlike his sister and his parents. :P

Danni Quee was Jacen's older woman interest. She was a scientist for the New Republic. Jacen saved her from Yuuzhan Vong captivity very early in the NJO and he had a small crush on her afterwards. She said they should just be friends and he accepted that quietly, the relationship falling off of the radar until much later in the series.

Danni Quee wass absent from Jacen's presence until Destiny's Way, when the two went diving together during Jacen's vacation. The scenes looked strictly friend-related, but it seemed to be turning into more during the Force Heretic trilogy. Throughout the FH series, Danni kept letting Jacen know how she felt about him, and Jacen kept acting oblivious towards it.

By the end of the NJO, Jacen seemed to shrug off mention of her casually, claiming to Jaina that 'he knows where she'll be' -- and Danni realized she didn't love him, the one line from her perspective closing the book on any romantic relationship:

"She owed her life to Jacen, and at one point had come close to falling in love with him."

Vergere was Jacen's mentor/teacher and also could be considered a student/friend. She met Jacen in Star by Star and from there they had a very rocky relationship.

Her constant riddles and crazy jive talk left Jacen utterly helpless in Traitor, until he realized that her jive makes sense and he owned everyone... but that's another story.

By the end of Traitor she proved to be a useful ally and an even better friend. After her death in Destiny's Way, Vergere talked to Jacen like Obi-Wan talked to Luke. And she still played an important role in Jacen's life and shaping later when he started down the Sithly path with Lumiya.