Unconscious

Unconscious is a condition in Fallout Tactics, Fallout 3 and Fallout: New Vegas. In Fallout 3 and New Vegas, unconsciousness is a result of what would normally be a death that happens to a character who is flagged as "essential" or, in the latter, any followers while playing off hardcore. When knocked unconscious, that person or creature will fall to the ground and lay there until the battle you are in is over, then get back up. If the person or creature was knocked unconscious by the player, they may remain hostile towards the player until they get back up. At some points in the Fallout 3 story, The Lone Wanderer will be beaten unconscious, such as getting captured by the Enclave or by the raiders in the Pitt.

An unconscious NPC cannot be looted/eaten/interacted with, but can be pulled along the ground for the short time until they regain consciousness.

Certain NPCs, such as Doctor Li or James are usually friendly, and will never turn hostile, no matter how many times you try to "kill" them. However, it may cause witnesses and corresponding allied faction members to become hostile for a short time.

If an essential NPC is hostile, rendering them unconscious will usually result in them getting up, friendly again.

In Fallout: New Vegas, companions will fall unconscious if they lose all their health. If Hardcore mode is turned on, however, they will die.

Additionally, the use of less-lethal weaponry such as the Boxing tape will render characters unconscious.
 * If your companion is knocked unconscious and you fast travel, you must 'Wait' and they will catch up to you.
 * This could be due to the length of Unconsciousness being in Real-Time, unlike Fast Travel which is instantaneous, though time passes based on how far you must travel as if you were walking.