In the initial dialogue with Dr. Klein as part of the quest Welcome to the Big Empty, the Courier finds out that their brain, heart and spine have been removed and replaced. This perk represents the replacement of their heart. While technically having these perks from the start of the add-on, they are unlocked in the course of the conversation.
Immunity to poisoning, -50% to Critical Chance for robots against the player character, and bonus healing with certain items. Stimpaks gain 10 bonus healing on use, and the following aid items gain five healing on use. This additional healing is displayed on the items themselves.
- Nightstalker squeezin's
- Thin red paste
- Blood sausage
- Black blood sausage
- Thick red paste
- Coyote tobacco chew
- Healing powder
- Leg. healing powder
- Human remains
- Bitter drink
- Since the Cloud in the Sierra Madre is corrosive and not poisonous, it will still hurt the Courier even with this perk.
- Heartless shares the same Vault Boy image as Cardiac Arrest.
- Cazadores, usually being very lethal creatures, become significantly less threatening even in swarms due to their damage primarily relying on poison. This makes battles with the Legendary Cazador and the later encountered Specimen 73 much easier than normal.
Behind the scenes
Heartless is an adjective associated with cruelty or a lack of remorse. Despite it's vernacular meaning it has no bearing on the perk's effects.
- Sink Auto-Doc message for this perk erroneously states "...allowing all healing items (chems) to function at a higher level (+25%)". [verification needed] The