The Echo Key was created by Benjamin Locke, in June 1775. Benjamin seemed to not know what function the key would have, and described in his journal that entering the Wellhouse, he was asked who he sought. When he said Joshua's name, his soul appeared, and Benjamin fled.
In October 1927, Chamberlin Locke tried to resurrect his late son John as an echo, but since John's soul was in Hell, his echo appeared severely mutilated and disfigured. Chamberlin collapsed and was tended to by Jean; John's echo besought his father to leave him be, for Hell was where he belonged, before fading away upon passing through the door.
When his mother passed away in 1987, Rendell Locke summoned her back as an echo to properly tell his mother that he loved her. In 1988, Rendell summoned his mother back to guard the extracted memories of Lucas Caravaggio after he was possessed by a demon. Ellie Whedon frequently visited Mrs. Locke at the Wellhouse to spend time with the memories. When she was followed by Dodge. Mrs. Locke tried to handle Dodge, but in a panic, Ellie pushed Mrs. Locke out of the Wellhouse, causing her to dissipate. After regaining his memories and killing Mark Cho to gain the Crown of Shadows, Dodge had a shadow hide the Echo Key along with the Gender Key and a memory he removed in Ellie's house as a backup in case his plans failed.
When Ellie uncovered the Echo Key in her house decades later, Dodge's memory fragment guided her to Wellhouse where she revived Dodge as an Echo. Dodge kept this key following his return, but as an Echo, he remained imprisoned inside of the Wellhouse for roughly a year.
After dueling with the ghost of Sam Lesser, Dodge accidentally dropped the Echo Key while escaping and left it for Nina to find. Recalling that Sam was fixated on magical keys, Nina presented the key to Daniel Mutuku to find out if it was connected to Sam's murder case. Daniel returned with the key later to Keyhouse, but from an ambush by Dodge's shadows, had the memory of this event removed, and the key was returned to Dodge.
Dodge kept the Echo Key with him once he took over the body of Bode Locke. After Dodge's plan falls apart by the Lockes, Rufus, courtesy of information given by Sam, used the Echo Key to open the Wellhouse and drags Dodge through, causing Lucas's spirit Echo to fade from Bode's body.
Two weeks after Dodge's defeat, Tyler kept the Echo Key on a keychain with the other keys. Tyler used the Key to summon Lucas back and free his soul from Dodge once and for all with the aid of the Alpha Key. He later used the Key to summon Rendell, who turned down Tyler's offer to return to the family as an Echo, and faded away as he hugged Tyler outside the Wellhouse.
Before going to face the Lockes, Dodge, in the form of Gabe, removes all of the keys that he has stolen from a vent in his door room wall. However, he places the Echo Key back, telling Eden Hawkins that it stays behind.
Following Dodge's destruction, the real Lucas returns, revealing that the key had brought him back as an Echo too and left Lucas trapped inside of his own body. As a result of being an Echo, Dodge's destruction by the Alpha Key didn't kill him like other demon hosts.
A week after Dodge's death, Eden recovers the Echo Key from where it was hidden in Gabe's dorm room. Eden uses it to summon the Echo of Captain Frederick Gideon, the first man to find the Black Door. Like Lucas and Dodge, Gideon is brought back along with the demon that had possessed him. Throwing Eden headfirst down the well, Gideon escapes the wellhouse using the Anywhere Key.
Sending two demons to recover the Echo Key, Gideon uses it to summon the Echoes of Samuel Coffey and James Bolton, two loyal human followers of the human Captain Gideon. During the siege of Keyhouse, Coffey is killed by a time-displaced Dodge who throws him through the Wellhouse door, causing the Echo to burn away. Bolton's Echo is eventually possessed by Sam Lesser through the Ghost Key, leaving Bolton trapped as a Keyhouse ghost.
With all the keys locked in the Harlequin Chest, the Lockes attempt to force Gideon across the Wellhouse threshold to get rid of the demon for good. However, Gideon manages to break free of their excavator and destroy the Wellhouse and along with it, the ability to destroy or summon an Echo using the Echo Key. Instead, the Lockes manage to use the Creation Key to retrieve the Alpha Key and use it to kill the demonic Gideon, throwing his body into a portal to the demon world.
When the Lockes toss all the keys into Gideon's portal, Bode tosses in the Echo Key.
The Echo Key is used to summon an "echo" of a dead person to the Wellhouse. Entering the Wellhouse, the user is asked: "Who?". Saying the name of someone summons their soul as a tangible Echo that rises from the well.
Echoes of the deceased are, for the most part, identical to their previous selves, but differ in a few ways. The Echo is trapped in the Wellhouse, as attempting to leave through the door results in the Echo fading away; the same holds true for an Echo that enters the Wellhouse. The Echo can only leave the Wellhouse through use of the Anywhere Key, where they technically aren't walking through the Wellhouse door. Additionally, an Echo inside the Wellhouse can communicate into empty spaces that produce echoes, both literally and metaphorically, as Sam Lesser's "emptiness" is what enabled Dodge to appear to him. Echoes also possess the ability to levitate, which they retain outside the Wellhouse, albeit it becomes physically exhausting to do so.
Chamberlin Locke speculated that an Echo "longs for the warmth and comfort of "that other place", and that using the Echo Key is selfish. Ellie Whedon also believed that Echoes are at peace, and therefore struggle to understand complex human emotion. An Echo may also reflect the status of the person's soul. For example, when Lucas was summoned, he was still controlled by Dodge after death; he explained that demons fear the "other place", thus they will cling onto their host's soul to prevent its return to peace, as Rendell corroborated. A condemned soul, on the other hand, can come back in a mangled, ghoulish form to reflect their perpetual torment in Hell, such as John Locke.
An Echo is essentially immortal, incapable of being killed in any way, with exception to crossing the threshold of the Wellhouse. Their invulnerability includes to injuries such as being shot, hit by a car, being in a car accident and then an explosion. If they are stabbed, an Echo will leave no blood on the knife. If an Echo crosses the Wellhouse threshold, they'll immediately and painfully burn up. However, they are subject to the rules of the other keys such as the Alpha Key being able to kill a demonic Echo and, if in the head of someone who dies by the way of the Head Key, dying with them.
While an Echo can't cross the threshold, a loophole exists in the use of the Anywhere Key to escape. This includes using the Anywhere Key to link another door to the main door of the Wellhouse. Gideon uses this part of the loophole to link the Wellhouse's storage room door to the main door of the Wellhouse. When Coffey and Bolton cross through the door, even though they emerge from the Wellhouse door, they are completely unharmed by the rule that would normally cause them to burn up.
Unlike human hosts, Echos can survive the Alpha Key being used to kill a demon possessing them. Normally the separation is fatal to both the demon and the host, but in the case of Echos, their invulnerability means that the fatal effects of the possessing demon's death doesn't harm them.
- Main article: Wellhouse
The Echo Key's door is the door to the Wellhouse.
- Joshua Locke (summoned by Benjamin Locke)
- John Locke (summoned by Chamberlin Locke)
- Rendell's Mother (summoned by Rendell Locke)
- Lucas Caravaggio (Dodge) (summoned by Ellie Whedon and Tyler Locke at various points).
- Rendell Locke (summoned by Tyler Locke).
- Frederick Gideon (summoned by Eden Hawkins).
Guide to the Known Keys entry
"whence I unlock'd the dore I heerd a voice that saimed to ecko from the well & is aisk'd me who I sot & I spake of my brother. No sooner had the words pass'd my lips thence he ROSE from the WELL like a spairt & yet was living flaish, alltho he had dyed in the Drowning Caves not 6 weeks beefor. He clasp'd me to his bosom & sayd why do ye look so unhappy to see me brother, but I wast in feer for my allmaighty SOUL & fled to the howse & pray'd thair to the LORD
But in that grait howse, an echo of my voice was all the reeply I receiv'd"
- Locke & Key: Clockworks #3, "The Tamers of the Tempest". December 14, 2012
- Locke & Key: Guide to the Known Keys. November 23, 2011
- Locke & Key: Hell & Gone #1. April 14, 2021
- Locke & Key: Clockworks #5, "Grown-Ups". March 14, 2012
- Locke & Key: Clockworks #6, "Curtain". May 16, 2012
- Locke & Key: Head Games #6, "Army of One". July 1, 2009
- Locke & Key: Crown of Shadows #1, "The Haunting of Keyhouse". November 11, 2009
- Locke & Key: Crown of Shadows #3, "Last Light". February 17, 2010
- Locke & Key: Crown of Shadows #4, "Shadow Play". March 17, 2010
- Locke & Key: Keys to the Kingdom #6, "Detectives - Part 2". April 27, 2011
- Locke & Key: Omega #1, "Our Regrets". November 14, 2012
- Locke & Key: Alpha #1, "Omega & Alpha", September 11, 2013
- Locke & Key: Alpha #2, "The End", December 18, 2013
- Locke & Key, Episode 9: Echoes
- Locke & Key, Season 2 Episode 7: Best Laid Plans
- Locke & Key, Season 2 Episode 10: Cliffhanger
- Locke & Key, Season 3 Episode 2: Wedding Crashers
- Locke & Key, Season 3 Episode 5: Siege
- Locke & Key, Season 3 Episode 6: Free Bird
- Locke & Key, Season 3 Episode 8: Farewell
- Locke & Key: Welcome to Lovecraft #2. March 12, 2008
- Locke & Key: Welcome to Lovecraft #5. June 11, 2008
- Locke & Key: Head Games #1, "Intermission". January 14, 2009
- Locke & Key, Season 3 Episode 7: Curtain
- Locke & Key, Episode 2: Trapper/Keeper