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Comparing The Mortal Instruments: City of Lost Souls to Shadowhunters


We’re back at it with another comparison between Freeform’s Shadowhunters and The Mortal Instruments: City of Lost Souls. Since this contains plot points of the show and books there are major spoilers ahead. I was going to postpone this post but likely the last episode was the conclusion of this book so I could post it sooner.

Check out my previous posts on how those books compared to Shadowhunters below. I’m not going to repeat minor differences (even if they are major) in this post since I’ve already mentioned them in previous ones:

Twinning Rune

Credit: Freeform

Oh Jonathan, you evil psychopath. The book and show handed this extremely differently. For starters, in the show Clary isn’t under the influence of Jonathan right away. He hates him, but slowly starts going dark. From burning her hands like him to standing up for him any time he’s mentioned. It’s only after she’s separated from Jace the twinning rune takes full effect and she goes to join Jonathan. In the book, Jace is under Jonathan’s influence immediately. Similar to how Clary would just pass off the Shadow world before the spell wore off. Jace’s mind just overlooks any negative thing about Jonathan so he helps Jonathan out with his plans.

Normally I don’t share my opinions on the differences but on this one, I just have to. Honestly I prefer how the show handles it. At this point in the books, I feel sorry for Jace. First, he’s lied to that the love of his life is his sister. Then he’s made to believe he has demon blood and is a monster. Then he dies and gets possessed after coming back to life. He gets freed only to be possessed again then at the end he has Heavenly Fire burning through his body so he can’t even really kiss his girlfriend. The poor guy just is not having a good few months. At least in the show, he has some breaks in between the events and instead of the final possession that goes to Clary. Granted he had to deal with the fact that he thought she died and the first possession was way worse. Still… it’s interesting plus Clary isn’t taken over immediately by Jonathan. She is still herself for a bit of time before then and we get some really cute Clace moments like them skating at the rink and sleeping together for the first time. Which has not happened in the books mind you, and can’t yet since Jace could accidentally burn Clary if his heart gets beating too fast. Plus Jace and Clary try twice before she’s taken over to get rid of the rune in the show. Once by the normal method of stripping a rune and the second by using the serum with traces of Glorious.

Seelie Rings

In the show, the Seelie Rings are used multiple times. First they are used by Valentine to communicate with Hodge, after both of their deaths the Institute still has them. Simon and Isabelle use the rings to infiltrate an underground Clave prison where they learn about Heavenly Fire serum that has particles of Glorious in it that turn Downworlders into mundanes. Then Jace uses the rings with Alec to spy on Jonathan and Clary after she’s fully gone dark. However, he is discovered with the rings after taking a Seelie drug with Clary and Jonathan trying to convince them he was on their side. As the ring only stays invisible if you are wake and focused. Well drugs mixed with kissing Clary is just enough to make Jace lose attention and the ring becomes visible. Jonathan recognizes the ring and has Jace attacked by Seelies. Clary helps him survive before sending him back to the New York Institute so he couldn’t get in the way.

In the book, the Seelie Queen asks Clary to steal them for her to tell Clary where Jace and Sebastian/Jonathan are. Clary does steal them after she sees Jace in the library with Sebastian, but decides to keep them for herself so she can use them to go spy on Jace and Jonathan to learn their plans. And she gives the second ring to Simon. The Seelie Rings in the book are visible the entire time the wearer has them on and it adjusts it’s fit for the individual who puts it on. They too go to a dance club but sometime after taking the Seelie drug they end up back at the apartment and Clary notices the Seelie ring is gone so she can no longer contact Simon to inform them on what Jonathan is after. As Jonathan took the ring away from her after talking with the Seelie Queen, since she had the ability to listen in on Clary and Simon’s conversations.

Removing the Mark of Cain

Similar to how Simon got the mark, the removal process in both the show and book are handled completely different. In the show, Simon has the mark removed by the Seelie Queen (whom he got it from) during a ritual that required the stone Cain used to kill Abel. He manages to survive the ritual and drinks Isabelle’s blood to prevent him from dying. In the book, in order to get Michael’s sword, Glorious, Raziel demands the stripping of the Mark of Cain which Simon agrees to. More Raziel wanted it to be removed from Simon as only God is supposed to give out that mark and he doesn’t want Simon bothering him for the rest of time, since Raziel could not smite Simon for summoning him.

Credit: Freeform


The archangel Michael’s sword. I already mentioned how Simon got it in the book. He summoned Raziel who gave the sword to him. In the show, the process to get Glorious is more involved. For starters, they had to get a serum of Heavenly Fire that contains a small portion of Glorious. Isabelle uses adamas mixed with what she could extract of Glorious from the Heavenly Fire serum and the angelic blood Simon has left over from Jace. These combined together allow Isabelle to forge Glorious to be used against Jonathan and sever his connection to Clary.

Magnus and Alec

I don’t really get too into Magnus and Alec in these comparisons as there is really nothing to compare. Magnus and Alec for the most part in the other books just isn’t there. In the last book, they spent seven weeks on a romantic vacation not that any of it was something we the audience were part of. So basically up until this book, we knew they were dating but without any details on it. With Jace being gone to Jonathan his segments are replaced by Alec so we actually get to see into his side of things. Alec is struggling with the fact that Magnus is immortal and the fact that one day Alec will get old and die. He is also extremely jealous of Magnus’s past lovers. Alec ends up meeting with Camille trying to figure out a way of either making himself immortal with dark magic or becoming a vampire. Then learns there might be a way to make Magnus mortal. Magnus is informed by Camille about this, and Magnus breaks up with Alec.

In the show, at this point in the story Magnus has lost his magic and immortality trying to free Jace from Lilith’s possession. Which made Magnus miserable as he lost part of him, granted he gave it up willingly to save Jace for Alec. Then Magnus gets magic replacement from the replacement Head Warlock of Brooklyn, but Magnus’s body rejects the magic and he almost dies. Alec planning on proposing to Magnus, hears the Magnus will never be happy again without his magic. To make him not miserable, Alec convinces Magnus’s father to give Magnus back his magic but the price was they had to break up without Magnus knowing the true reason. Alec agrees as he just wants to make Magnus happy, even though actually makes the two of them miserable. Maryse (Alec’s mother) goes to Magnus to talk to him trying to figure out what happened and points out to Magnus why suddenly he got his magic back.

Jonathan’s Apartment

In the show, the apartment Jonathan stays in belonged to Lilith. It was just a regular apartment that could be moved based on ley lines using demonic abilities. It was one floor and the front door was an elevator door from when it was a pentahouse. The girl clothes inside that Clary wears belonged to Lilith. When Jace joins Jonathan and Clary, Jonathan doesn’t trust Jace but lets him stay for Clary. Jonathan after Team Evil kidnap the Seelie Queen teaches Clary how to control and move the apartment.

In the book, the apartment belonged to Valentine where Jonathan was raised some of the time after Valentine left Idris. He had stocked up the two floor apartment with clothes meant for Jocelyn in case she ever came back. When Clary joins Jace and Jonathan as a spy, she wears those clothes as she didn’t bring any with her. Jonathan is also completely aware she doesn’t trust him and isn’t just going to join in on their plan. He lets her stay, because he knows it’s what Jace wants. Right before they leave for the Dark Ritual Clary destroys the apartment with a rune, after nearly being raped by Jonathan.

Credit: Freeform

The Iron Sisters

We are introduced to the Iron Sisters and the Adamant Citadel at very different times in the show and book. In the show, Clary and Isabelle go to the Citadel after Valentine steals the Soul-Sword to learn why he would take it. The Citadel is on a mountain but not hard to travel to. Before they can enter, both have to take a purity test. Clary passes but Isabelle fails do to her taking yin fen after the demon attack at the Institute. Clary goes inside with Cleophas who is Luke’s sister.

In the book, Jocelyn and Isabelle go to the Adamant Citadel which is located in a volcano. There is a chasm separating the Citadel from everything else and only the blood of a Shadowhunter on the good side of the Clave can make the bridge come down to cross. Isabelle and Jocelyn talk to Sister Cleophas (who is not Luke’s sister in the book but rather his mother) to learn about a sword that can hurt Jonathan but not Jace. She informs them that only a Heavenly sword could do that, but they would be unlikely to get one from the angel after the wish was used.


This greater demon is summoned to Earth in both the book and show, but by different people and for different reasons. In the show, Jonathan used Azazel to leave Edom the first time and allows Azazel to go free as payment for the deal. Azazel is later summoned by Magnus in order to banish him but instead Azazel switches Magnus and Valentine into each other bodies so Valentine as Magnus could give Azazel the mortal cup. Alec later kills Azazel when Valentine is working on how to get to Idris to retrieve the cup.

In the book, Azazel is summoned by Magnus in order to figure out if there is a demonic way to separate Jace and Jonathan since there appeared to be no way to get a heavenly sword. Azazel agrees to tell them his plan if each member in the summoning (Simon, Isabelle, Magnus and Alec) give up a happy memory. They agree to this and Azazel informs them he would take Jonathan to Edom where Jace would be save from harm and in time the connection may weaken or sever, but in return wants to be free to roam earth. Magnus banishes him as the group debated on what to do.

Jonathan’s Plan

The apartment can go anywhere in the world, and in both the show and book one of the locations they end up is Paris. In the show, Jonathan is looking for the Morning Star Sword stating it’s a family heirloom that he wants back. They start out by going to a demon named Merik and learn he sold the sword earlier. Jonathan manages to track it down to the Seelie Queen. So they plan on ambushing her while she’s at a night club to get the sword. Jace is found out to be a spy during this and after he fights off Seelie Knights, Clary sends him back to New York through one of her portals. Jonathan and Clary were able to kidnap the Queen from the club. Jace and Isabelle take Glorious to the Wandering Woods where Clary and Jonathan are arrived to get the Morning Star Sword which can control demons from the Seelies’ in exchange for their Queen.

In the book, Jonathan and Jace go to Merik to get adamas not the Morning Star Sword. Then they take that to a disgraced Iron Sister so she can forge them a new Mortal Cup that Jonathan can use to create dark shadowhunters that work for demons not angels. Clary learns about the true plan after Jace gets the new cup and has the Twinning Rune temporarily damaged so he is himself again without Jonathan having any idea of what’s happening. Jace also informs Clary that the Infernal Cup was his idea but the rest of the plan was Jonathan’s. Clary informs Jonathan, Jace is free of the possession so Jace cannot turn himself over to the Clave. Jonathan uses the Infernal Cup with Lilith’s blood to create 40 or so dark shadowhunters, each after drinking from the cup lose their marks and can’t use the seraph blades anymore. Jonathan almost forced Clary to drink from the cup too but she manages to break away.

Credit: Freeform

Breaking the Connection

In the book, Simon brings Glorious to the Jonathan’s ritual and gives it to Clary after she manages to escape from Jace’s grip who was holding her behind the new Endarkened army. As Clary cannot get to Sebastian after getting Glorious, she piercing Jace through the chest with the sword. This destroys the Twinning Rune between Jace and Jonathan. But leaves Jace with Heaven’s Fire so any time his heart races it starts to burn anything around him. After she stabs him the sword vanishes with the group believing it returned to Raziel since the sword was just on loan.

In the show, Clary fights with the Morning Star Sword Isabelle who has Glorious while Jace fights Jonathan with Alec assisting. Jace handcuffs Jonathan as they got the upper hand. Clary and Isabelle knock the swords away from each other. Just as Alec goes to kill Jonathan, Jace stabs Clary separating the two of them. Jonathan then grows black wings and gets the Morning Star sword. As now he’s fully a demon instead of a Shadowhunter. Clary is free of Jonathan and the Twinning rune is gone! As the sword is unstable, Glorious explodes after stabbing Clary with Simon being protected by Isabelle but she is hit by the debris of the explosion. Clary is racked with guilt over betraying everyone especially Jace. After she takes the apartment to Alicante with Isabelle, Alec, Simon, and Jace inside it with her.

Minor Details/Differences

Credit: Freeform


  1. Jace is tied to Jonathan.
  2. Simon was seeing Isabelle after Valentine’s death, separated for a bit but got back together.
  3. Jocelyn and Luke are engaged to be married.
  4. Jonathan has blond hair.
  5. Clary was found innocent for making the Wish as she technically wasn’t the one to summon Raziel in the first place.
  6. Everyone searched for two weeks for Jace and Jonathan before the priority was lowered.
  7. Helen is introduced as Aline’s girlfriend after Clary is found innocent.
  8. Jonathan actually goes by Sebastian as he doesn’t want to be associated with the name his parents gave him.
  9. Maureen kills Camille and becomes the new leader of the New York vampire clan.
  10. Maureen is the feral new vampire and has Praetor Nick assigned to her case and is killed trying to stop her.
  11. Luke has a sister named Amatis.
  12. Luke is severely injured with a demon blade and needs Praetor help to survive.
  13. There is an Infernal Cup, but no mention of the Morning Star Sword.
  14. Raziel is summoned.
  15. Magnus never loses his magic.
  16. Jace and Clary almost had sex, but didn’t as Clary thought it was wrong while he was still possessed.
  17. Jonathan tries to rape Clary, but stops after Clary almost kills him. She stopped so Jace wouldn’t die as they were still linked.
  18. Jonathan thinks of Lilith as a mother and brings her back from the Void. As well as use her blood to create the Endarkened Shadowhunters.
  19. Max died during the events of the Mortal War.
  20. Simon’s mom knows he’s alive but calls him a monster, this prompts Simon to move out and live with Jordan.
  21. Magnus and Alec break up.


  1. Clary is tied to Jonathan.
  2. Isabelle and Simon realize they like each other, but still have not had their first kiss.
  3. Jocelyn is dead and Luke has just started seeing Maryse.
  4. Jonathan has dark red hair.
  5. Clary was found guilty for making the Wish.
  6. Only Luke believed Clary was still alive, later convinces Jace she might still be alive so they search together to find her using atmospheric pressure.
  7. Helen is introduced as working with Aldertree on a Heavenly Fire project that turns Downworlders into mundanes.
  8. Jonathan goes by his birth name.
  9. Maureen isn’t around anymore, after Simon slept with her back in season one.
  10. Heidi is the feral new vampire obsessed with Simon. Praetor Nick is killed while they were trying to capture her.
  11. Luke has a sister named Cleophas and Amatis.
  12. Jordan Kyle is injured by a silver dagger after Heidi orchestrated an attack on the werewolves. He goes to the Praetor for help but they couldn’t save him.
  13. There isn’t an Infernal Cup, but there is a Morning Star Sword.
  14. Raziel is not summoned.
  15. Magnus loses his magic twice.
  16. Jace and Clary have had sex.
  17. Jonathan tries to kiss Clary.
  18. Jonathan hates Lilith and agreed to deliver her head on a Silver platter to the Seelie Queen in exchange for the Morning Star Sword. Though that was unsuccessful.
  19. Max is alive.
  20. Simon’s mom believes he is dead due to his compulsion and moved to Florida with his sister Rebecca.
  21. Magnus and Alec break up temporarily then propose to each other.

Love ya,

Mae Polzine

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