They may be able to help her find her old Master. Sebille believes that there are Lone Wolves somewhere in the region.
Sebille knows that Roost Anlon was seen somewhere in the region. Sebille died on the Lady Vengeance as we tried to escape Dallis' attack. The Lady Vengeance told us that the Mother Tree intends to spread her roots throughout the entire world and make it her own. The Lady Vengeance told us that it was controlled by a slave scar - the same kind of scar that Sebille has. To find this master, she must seek a Lone Wolf by the name of Roost Anlon, as it was he who first kidnapped her and sold her to her Master. She's looking for her Master, who once enslaved her. She must travel to Reaper's Coast and track the bastard down. If anyone knows where the Master is, it is him. Sebille learned that it was a Lone Wolf called Roost who sold her into slavery to the Master years ago.
She instead said that Sebille will have to discover it for herself. Sebille met with a blind elf named Saheila, who recognised something in her, but wouldn't say what. If she manages to find him, that'll be her chance to question a Lone Wolf. Sebille met with Griff and learned that there's a Lone Wolf smuggler out in the swamps known as the Hollow Marshes. Her next clue is to look into a mercenary band called the Lone Wolves. Before dying he told her only her Master can remove the scar she seeks to be rid of. Sebille tortured and killed Stingtail, a lizard Dreamer. He will tell her that she needs to speak with Zaleskar in the Hollow Marshes you will meet after you escape Fort Joy. Speak to Griff with her who is is located in the Fort Joy Ghetto.Interact with him and she will kill him ( Warning: Stingtail is involved in several quests make sure you do them before you kill him) and you will get a new journal entry. Follow Stingtail until he goes to sleep.You acquire her quest when she joins your party.See Hunt for the Master if your main character is Sebille.This is Sebille's companion quest in Divinity: Original Sin 2.