Isabelle Lightwood

Isabelle "Izzy" Sophia Lightwood is a Shadowhunter and lives in the New York Institute. She is rebellious and very beautiful. Her cooking is often made fun of by Jace and Alec. She is known to be dangerous and often carries weapons in her tall boots that are never less than seven inches.

Her signature weapon is a whip with which she is quite skilled. She dresses well, as shown when she gave Clary to wear clothes that she picked for Magnus's party. Despite this seemingly shallow and girlish side of her personality, she is shown to take responsibility for situations, shouldering the blame for her brother Max's death, despite having been struck unconscious at the time. She is comforted by Simon, and ends up sleeping (in a literal, non-sexual sense) with him. She begins to casually date Simon—who is also dating Maia at the same time—and then later upon finding out about Maia, breaks up with him. After this and seeing how she is genuinely hurt by it, begins to slowly realize that she may actually be in love with Simon, but refuses to admit it.

Isabelle obviously cares for Jace and Alec, and is fiercely protective of both of them. Because of this, she is constantly torn over the fact that her brother is struggling with his sexuality and when Jace is heartbroken over Clary during whatever problem he has with her. In City of Glass, she yells at Clary for only thinking of herself and not realizing how much pain Jace is in due to how much he really loves her.

Physical appearance
Isabelle is very beautiful and tall. She has very dark brown eyes with hints of gold that initially appear to be black. She is curvaceous and has long black hair that is described as "black as spilt ink" by Clary. She dresses stylishly, often with high heels. However, she despised her height and hated towering over everyone and wished to be small and delicate.

She is portrayed by Jemima West in the film adaptation of the book, and Emeraude Toubia in the television series.

Family
Isabelle is the middle child in the Lightwood family. Her parents are Maryse and Robert Lightwood, who were once in the Circle with Valentine until the Uprising. Her older brother is Alec and her younger brother was Max, who died at the hand of Jonathan Christopher Morgenstern. Jace is her adoptive brother. Her parents run the Institute in New York.

Isabelle's love interests

 * Simon Lewis: Simon is obviously smitten with her when they first meet, but she never treats him as anything more than a "mundane" until after his transformation into vampirism. As a vampire, he gets deeper into their world and they become friends. They spend the night together (non-sexually) when Simon attempts to comfort Isabelle after Max's death which she blamed herself for. Isabelle is shown to be jealous of Maia, who also liked Simon. Isabelle's feelings for Simon deepen later into the series, though she refuses to admit that she may be in love with him. In City of Lost Souls, she eventually admits that she thinks about Simon all the time and "nothing like this has ever happened to [her] before". However, she struggles with her feelings and telling Simon how she feels about him, believing that the guy should make the first move (contradicting with Simon's personality who, as stated by Clary, thinks that if a girl does nothing to indicate any romantic feelings must mean that she doesn't like him).
 * Meliorn: Meliorn is a knight of the Seelie Court and later the Seelie representative on the Council. In City of Heavenly Fire he is found out to be half-human half-faerie and is killed by Alec. He and Isabelle had a brief fling and the Seelie Queen hearing about this had him pass on a message to request an audience with Clary, Isabelle, Jace, Alec and Simon.