A known alternate dimension, or alternate timeline, is one where demons have been defeated for a long time, and thus the concept of Shadowhunters no longer exist. Shadowhunters and Downworlders alike have long conformed to the mundane way of life. This dimension can be reached from the one occupied by Clary Fairchild and the others through a gateway in the Seelie realm.
The Shadowhunters of this world won the war against demons, defeating them and successfully closing the rift between their worlds. Because their services were no longer required, their culture faded away and eventually became forgotten even by Shadowhunters themselves. The Downworlders conformed to the mundane way of life to avoid detection, and some warlocks have stopped practicing magic.
This peace was almost disrupted when a Ravener demon entered their realm, after the passageway that was left open for Clary Fairchild, who came into the dimension in search of its last Portal, was attacked. Clary and Jace were able to defeat the demon, and the Magnus Bane of this dimension closed the Portal after they left to finally, completely seal their world off from demons and from the other dimension.
There are several distinct similarities and differences between this dimension and that of the one we know.
Because they were no longer Shadowhunters, Valentine never founded the Circle. He lived happily with his wife and daughter in New York City. Valentine was instead the founder of the Institute, an innovative Internet company. Isabelle Lightwood was a nerd who worked under him as a developer. Her brother Alec was openly gay and planned the Institute's 10-year-anniversary party, themed with Through the Looking Glass elements upon Valentine's request. Clary was still best friends with Simon Lewis, who was in a relationship with Isabelle and was about to ask the latter to move in with him. Clary was still in a relationship with Jace, who works at Java Jones; because of his lack of Shadowhunter training and upbringing, Jace was cowardly and freaked out by the appearance of a demon at the Institute.
Meanwhile, Magnus Bane was still immortal but no longer practiced magic. He instead opened up a psychics shop, where he gave advice to those who sought it. apparently upon his advice, Luke Garroway left the police force and opened up a bookstore while Hodge started a dojo.
- If an outsider enters the dimension, they take over the body of their counterpart in that dimension. The longer they stay inside, the higher the risk that the outsider could be assimilated into his/her counterpart's body, forgetting his/her life outside, and disappear from his/her own world forever.
- 1x10: This World Inverted