Nothing is known about Sullene's life prior to or as the outbreak began.
Sullene first appears raiding the Boarding School with other members of Delta. During the raid, she follows Clementine inside the school with Abel and Yonatan, witnessing the latter's death by a trap activated by Clementine herself. At the staircase she gets pinned to the wall by a sofa pushed down by Clementine.
During the raid, Clementine can shoot Sullene in the back with an arrow to save either Louis or Violet (Determinant), based on whoever Clementine didn't hang out with earlier. Alternately, she can successfully kidnap them and put them in a carriage. She then runs off with Lilly and Dorian, along with a kidnapped Omar, Aasim, and Louis/Violet.
Sullene can be seen defending the S.S. Stewarts Fitzgerald from the incoming walkers. This causes her to be oblivious to Clementine and her group sneaking on board the boat.
Later on, if Clementine told AJ to kill Lilly, then Sullene will go back up to the top of the boat after she hears gunshots. After she finds out that Lilly was killed by AJ, she becomes furious with the group and threatened to kill them. However, before she can do anything, the bomb explodes.
After the destruction of the boat, Sullene can be seen fighting off walkers on the shoreline alongside the other surviving Delta raiders. She eventually spots Ruby and Willy and orders Gina to shoot them. After Gina is shot and killed by Clementine, a furious Sullene pulls out a pistol and attempts to shoot Clementine in revenge, only to be attacked and devoured by the approaching walkers.
- Killed By
As Sullene attempts to shoot Clementine in revenge for Gina's death, she fails to notice two walkers sneaking up behind her. As a result, she is bitten several times and devoured.
This list shows the victims Sullene has killed:
- Herself (Indirectly Caused)
- Numerous counts of zombies and possibly unnamed people
- "Lilly, we couldn't find the other... What did you do? You are fucking dead!"
- —Sullene to Clementine if Lilly was killed. (Determinant)[src]
Sullene and Lilly seemed to have a good relationship. After AJ (Determinant) killed Lilly, she will become furious and would attemped to kill AJ for doing so. If Lilly is alive however she will flee the sinking boat, leaving Sullene and the other Delta members to die. (Determinant)
Sullene and Yonatan seemed to be somewhat close, as after Yonatan's death, she became furious, shooting at and trying to kill Clementine as a form of revenge. The exact extent of their relationship however, is unknown.
- With her death in "Take Us Back", none of the members of the Delta's group that attacked the boarding school are alive, if Lilly was not spared in "Broken Toys".
- Sullene is the first character to be killed by walkers on-screen in Season 4.
- Originally, Sullene was going to be the final Delta member that attacked Clementine, Tennessee, and Violet/Louis (Determinant) on the covered bridge, seeking revenge for the S.S. Stewarts Fitzgerald's destruction and the killing of many of her allies. This was cut due to the fact that Sullene's role was very small and Minerva being the last one standing was more impactful and carried more dramatic weight.
- Sullene was planned to be in a relationship with Yonatan at an early stage of development, explaining her reaction to his death. 
- Marcela Páez voices Sullene in the Spanish version.
- Dagmar Dreke voices Sullene in the German version.
- Vany Américo voices Sullene in the Portuguese version.
- Corinne Wellong voices Sullene in the French version.