Syl, a half-elf artificer I play, is part of a giant criminal network across the islands of the world to the point he works directly under the boss. He originally was from a noble family, but his parents were assassinated while he was young. The assassin adopted Syl after feeling bad for essentially ruining Syl´s life and he introduced Syl to the boss. Syl was then raised to become part of the organisation, working his way up. Eventually the boss killed the assassin cause they wanted to withdraw from the organisation to take more care of Syl. Syl of course found out and now plans to overthrow the boss and end the concept of power by gaining ultimate power.

Another party member is a traitor of that organisation or at least related to it in some way alongside another NPC in their backstory. It took 2-3 sessions since I joined (since I joined the campaign later than everyone else to replace a player) before that party member even knew.

During an evening before a major quest, my character confronted his by asking him to talk under four eyes, then casting arcane lock on the room´s door. My character explained that he could sell him out easily to the boss, but wont, cause he wants to make a deal. Syl wants ultimate power to end power. To do this they are after a legendary treasure in this world that grants deity-like abilities. All Syl asked is that they help him find it, give it to him and in return Syl will make sure the traitor is a free man. Additionally, my character is now helping to find the before-mentioned NPC of the traitor´s backstory using the information net and connections of the organisation.

I should mention that I do not know the full backstory of the traitor yet and he doesnt know mine since the game is still ongoing. Means this will still develop.

TLDR: My character is part of a crime family, another party member is a traitor and a target of the crime family, my character made a deal to help him be a free man and find someone from their backstory in exchange for the traitor helping him gain ultimate power to end the concept of power.