The Trust System is one of the unique and defining features in both versions of Splinter Cell: Double Agent, with it having both drastic and subtle influences on the game as a whole. For example, the level of trust will affect just how characters will act towards the player, outcomes of certain situations, and also what equipment and upgrades the player can access.
Version 1 Edit
In Version 1, the Trust System is visually represented by two bars, one belonging to the JBA while the other belongs to the NSA. The bars will fill or lower for the respective faction depending on whether you supported them or undermined them in a particular objective. If either of the faction's bars drop to 0, then the game is over. Unlike Version 2, the player can effectively keep both factions filled up by performing side objectives for both factions.
Version 2 Edit
In Version 2, the Trust System appears differently - instead of two bars, the player only tracks one. The JBA appears on one side of the bar, while the NSA appears on the other side - with a 'slider' in the center representing the player's position between both factions. If the player helps one faction more than the other for too long, the game is not over: instead, the faction with the lowest trust to the player will instead give the player an opportunity objective during any of the missions to gain back trust.
- In Version 1, NSA Trust is needed in order to get the 'Hero' ending, where the true final level - Coast Guard Boat - is available to the player.