Eagle Vision

"Why do we have these gifts? These abilities? Because it's in our blood!"

- Clay Kaczmarek about Eagle Vision.

Eagle Vision was a sixth sense that certain lineages of humans possessed, as a result of being created by the First Civilization. Though every human held the potential for it, bloodlines of humans who interbred with their creators held a greater concentration of the necessary genes, and were thus more likely to exhibit the ability.

Those who possessed the gift were able to instinctively sense how people and objects related to them, which manifested as a colored glow, much like an aura in a person's mind's eye.

When an individual learned to master Eagle vision, the ability evolved to the more advanced Eagle Sense. This heightened all of the senses of its user, allowing them detect the heartbeat of a target in the area, or even foresee a target's path.

For both Eagle vision and sense, the same variety of colored glows was used to mark different people or objects. Red indicated enemies or spilled blood, blue indicated allies, white indicated sources of information or hiding spots, and gold indicated targets or any person of interest.

Third Crusade
The Assassin Altaïr Ibn-La'Ahad possessed Eagle vision from an early age. His fellow Assassins knew of his special ability as well, and were the ones to dub it as "Eagle Vision."

With it, Altaïr found himself able to read the emotions and intentions of all those around him, driving him to perfect the ability in secret. In his later life, he would make use of it during his many assassinations and investigations.

Eagle vision aided Altaïr in locating targets, and was particularly useful during his duel with Al Mualim, who used the Templar treasure to create phantoms of himself. With his ability, Altaïr was able to pinpoint the true one from the crowd.

Ezio Auditore
"Listen closely: Return to the house. In my office is a hidden door. Use your talent to find it."

- Giovanni Auditore instructing Ezio to use his Eagle vision.

Ezio Auditore, much like Altaïr, possessed Eagle vision, and made use of it to locate hidden passages, as well as to predict the intentions of his allies and enemies. Additionally, he was also able to see the map hidden beneath the pages of the Codex with it.

Though never referred to explicitly as "Eagle vision," Giovanni Auditore once referred to Ezio's ability as his "talent," and Salaì spoke of it as his "gift."

The Assassins of Constantinople also knew of Ezio's ability, even before they had met him. When Piri Reis instructed him to use it to see through a smoke screen, Ezio pretended not to know what he was talking about, but Piri merely answered that "word gets around." At hearing this, Ezio suggested he keep the information to himself.

Yusuf Tazim spoke of Ezio's skill as his "legendary senses," and Piri once mentioned that Ezio was a "special sort of man, with strange gifts." Ezio himself also admitted that his senses were "more finely tuned than most."

Others
"The note told me to use my other eyes. Sometimes I see things that are not there. Drawings, or waves."

- Giovanni Borgia describing his Eagle vision.

La Volpe was thought to possess an advanced form of Eagle vision, as it was claimed he could "look through walls."

Giovanni Borgia also had Eagle vision, and was able to use it to locate and tail Francesco Vecellio through a crowd. With it, he was also able to see images and drawings that were not really there. Francesco referred to the ability as "using his other eyes."

Assassins
"Try using that special sight you learned from Altaïr."

- Lucy Stillman to Desmond Miles in the Sanctuary.

By using the Animus to follow the memories of his ancestors, Desmond Miles also gained the ability to use Eagle vision, likely as a result of the Bleeding effect. Through it, he was able to see Lucy Stillman (a fellow Assassin) glowing blue and Warren Vidic (a Templar) glowing red.

He was also able to use this ability to see the cryptic messages that Subject 16, Clay Kaczmarek, had written in the Abstergo laboratory with his own blood.

During his escape from Abstergo Industries, Desmond found another application for his newly-acquired power. Much like thermal vision, he used it to discover the code of a keypad, by seeing the heat signature or the fingerprints left upon the correct numbers.

In a video clip hidden within one of his Glyphs (which needed to be scanned with Eagle vision to be unlocked), Clay stated "Why do we have these gifts? Because it's in our blood." This implies that, because Altaïr, Ezio, Desmond and Subject 16 all have Eagle vision, their bloodline is connected to the joining of humans with the First Civilization.

Later, upon escaping to Monteriggioni, Desmond was also able to use Eagle vision to see a message Ezio had left upon the wall of the Sanctuary stairwell, which bore the password to the Colosseum Vault.

Templars
Abstergo recruits using Animi to hone their skills were also granted an ability called Templar Vision. This rendered ability mimicked Eagle vision, and allowed the user approximately 3.5 seconds of the gift.

Eagle Sense
"As Ezio matured, so did many of his stranger abilities, not least of which was a rare form of extrasensory perception - you know, what we Assassins call "Eagle Sense" in its most robust form."

- Clay Kaczmarek.

Mastering Eagle vision led to an "awakening of the sixth," as Juno once termed it, and granted the user Eagle sense.

A more heightened form of Eagle vision, it allowed one to focus on a target, and sense approximately where they had gone, or inversely, where they would go. This was particularly helpful in tailing a target, or detecting the path a guard would take, in order to set up a bomb or lay an ambush.

With Eagle sense, Ezio was also able to pick up cold trails, or locate disguised enemies. However, for this latter one, he was required to concentrate harder, and needed to scrutinize people individually, rather than as a crowd.

Similarly to his method of detecting hidden enemies by listening for heightened heartbeats, Ezio also once used his Eagle sense to diagnose an injured mercenary, concluding that the man was alive but weak, and likely affected by some form of poison.

Trivia
Assassin's Creed
 * An Assassin guard can be seen glowing red in the Kingdom entrance to Masyaf, but he reacts in normal guard behavior. This guard was originally intended to have be Jamal, an Assassin who aided Masun in betraying the Brotherhood; however, the sequence where Altaïr assassinates him was cut from the final game, leaving him as a minor Easter egg.
 * In the original Assassin's Creed, movement is restricted while using Eagle vision, and Altaïr is required to be at maximum synchronization. These requirements were removed in succeeding games.
 * In Assassin's Creed, Eagle vision is said to actually just be the Animus' visualization of the Assassin's observational skills.

Assassin's Creed II
 * The users of Eagle vision see themselves marked with blue.
 * At the beginning of the game, while playing as Desmond in the Hideout, you will see equipment shine blue in Eagle vision. This indicates that they can be used for free-running.
 * Lucy makes a reference to the ability by saying "Open your eyes, Desmond," when Desmond asks her how to find the Hideout's defense system sensors, which she had tasked him to switch on.

Assassin's Creed: Brotherhood
 * When traveling through Rome, Eagle vision can be used to mark Flags, Feathers or Treasure chests on the map.
 * While using Eagle vision and roaming Monteriggioni as Desmond, a red trail is visible leading from the fountain with the Assassin insignia, until the door to Mario Auditore's study. The trail is colored similarly to the blood glyphs of Subject 16, and appears to be made up of many footprints.
 * An interview with Darby McDevitt and Falko Poiker explains that the trail was intended to help gamers find their way back to the Sanctuary, though its red color was a developer oversight.
 * When outside of the Animus, there is sometimes a pause that causes allies to glow gold for a few seconds.
 * Unlike in Assassins Creed II, enemies and allies do not glow their standard colors after they die, and will appear grey like civilians and inanimate objects.
 * In some memories, water is shown to be glowing white like hiding spots when Eagle vision is activated.
 * When dressed as a Borgia guard captain in the memory "When In Rome," if Eagle vision is activated, the armor will glow red, though Ezio himself will still be marked with blue.
 * Unlike Eagle vision, Templar vision marks targets with blue rather than with gold, since they are hunting other Templars and can be considered allies in a contained session.

Assassin's Creed: Revelations
 * During Ezio's pilgrimage to Masyaf, and Altaïr's return from exile to Masyaf, the player can see ghostly images from Altaïr's past.
 * Unlike normal enemies, the paths of officials and the two guards accompanying him cannot be tracked.

Others
 * A mini-game in the Assassin's Creed room of PlayStation Home features an Eagle vision puzzle that, when completed, opens up the Hideout.