The Heart

"With this Heart, you will hear many secrets."

- The Outsider, giving Corvo the Heart

The Heart is a mystical object the Outsider gives to Corvo Attano to assist him throughout the events of Dishonored, and to either Corvo or Emily Kaldwin to help them in Dishonored 2.

A vessel designed to contain a spirit, it is used to help uncover runes and bone charms hidden throughout the Empire of the Isles. It starts beating and lights up when turned toward supernatural objects in the area, and beats faster as the protagonist gets closer. In addition, when one squeezes the Heart, it whispers secrets directly into their mind concerning the current area, as it senses information about the world beyond mortal recognition. When the Heart is pointed at a person, it reveals secrets about them.

A list of the Heart's secrets in Dishonored can be found here.

A list of the Heart's secrets in Dishonored 2 can be found here.

Origins
Created by Piero Joplin after a vision from the Outsider, the Heart is given to Corvo during his first visit to the Void – the Outsider delivers it personally, referring to it as "the Heart of a living thing, molded by my hands."

Granny Rags hints during the House of Pleasure mission that the Heart was crafted from that of Empress Jessamine Kaldwin after her death. When Corvo encounters Granny Rags in the alley behind the Golden Cat bathhouse, she tells him, "Nothing's been the same since her [the Empress'] death! Poor child! Her spirit lives on – trapped – misused – and for what purpose?"

The Heart itself also hints at such origins through various instances of dialogue:
 * During the elimination of Hiram Burrows in Dunwall Tower, the Heart tells Corvo that "we (the Heart and Corvo) have both been here before," when used on the exterior of the building. When pointed at the Regent, it says "I was a fool to trust him."
 * When the Heart is used on Farley Havelock, it has noticeable difficulty recalling details of the Empress' death.
 * In regard to Anton Sokolov, the Heart claims, "He knew me once. And did much to set me on my path."
 * When using the Heart on Daud, it remarks, "Why have you brought me here? Am I meant to forgive this man for what he did?"

It has been confirmed in Dishonored 2 and by Harvey Smith that the Heart indeed belongs to Jessamine.

Function
In Dishonored, the main function of the Heart is to reveal the locations of runes and bone charms, as well as secrets about people and the general world. After the events of Dishonored, the Heart seemingly returns to the Void.

In Dishonored 2, either Emily or Corvo obtains the Heart from the Void when they first visit it between the missions A Long Day in Dunwall and Edge of the World. Here, Jessamine's spirit appears and talks to the protagonist, before resuming its normal function. During the mission The Grand Palace, Jessamine's spirit finally leaves the Heart, ceasing to exist, and is replaced with Delilah Copperspoon's spirit. The Heart shows this change by becoming blackened around the transparent screen. When the protagonist returns to Dunwall Tower in the mission Death to the Empress, the Heart is used to return Delilah's spirit to her body. Empty of a spirit and not immediately filled by another one, the Heart disintegrates.

Trivia

 * The Heart is voiced by April Stewart, who also voices Empress Jessamine Kaldwin.
 * According to Harvey Smith, "... others don't see [the Heart]. Corvo pulls it out of thin air."
 * Due to the occult nature of the event at his house in 1849, Aramis Stilton can see the Heart, and tells the protagonist to put it away. He is also aware that others cannot see it.
 * A tweet from developer Harvey Smith claims that the spirit within the Heart is still trapped after Dishonored's end, and will be "free once there's no one marked by the Outsider for whom she feels intense love/protection".
 * Events in Dishonored 2 override this statement.
 * The Heart cannot be stopped by music boxes, despite being connected to the Void.
 * A replica of the Heart is housed at the Academy of Natural Philosophy.
 * Prior to his expulsion, it is rumored that Kirin Jindosh – now Grand Inventor to the Duke of Serkonos – made a functional version of the Heart that operated for exactly 13 minutes before turning to ash.
 * The Heart has a maximum detection range of 250 meters.
 * It also cannot detect runes in another map, but that is a limitation of the game, not the Heart.
 * The Heart has limited precognitive powers, as Jessamine appears to the protagonist before the mission The Grand Palace and tells them that it is her last night in the world.
 * The Heart can also talk of its own free will, not just when prompted, but does so rarely.
 * In The Flooded District, after the protagonist loses the Heart, if they find themselves close to a rune or bone charm, the game will still display the message "Rune or Bonecharm nearby. Equip the Heart."
 * The spirit in the Heart can take on a visible shape, but without the ability to interact with the physical world. It does this a few times during Dishonored 2.
 * It is never explained exactly how Piero obtained Jessamine's heart. The developers never worked it out either.
 * In The Grand Palace mission, when the spirit in the Heart is replaced:
 * It is removed from the quick slots and has to be mapped again.
 * Delilah's spirit will say the following "She found the place where he was birthed by knife and ritual, thousands of years past." referencing the events that led to the Outsider's creation.