Born in 1863, Cecily is the youngest of the three children of Linette and Edmund Herondale. Cecily and her siblings were raised in Wales, believing that Shadowhunters were monsters. When she was nine years old, her older sister, Ella, died of demon poison after the demon Marbas was released from a Pyxis by her brother, Will. For reasons they could not understand then, Will, racked with guilt and fear, ran away from home and went to London to become a Shadowhunter.
Hearing from Will
Cecily and her parents never really forgot about Will, and vice versa. In 1878, it was Cecily's name that Will called out to while he purged himself of vampire blood, leading Tessa to believe that Cecily was someone whom Will was romantically involved with since Will rarely talked about his past.
After almost two years of living in peace and isolation in the country manor in Yorkshire, Will found them in 1878 while on a job for the Enclave. Will, along with Jem and Tessa, saw Cecily, in particular, coming home to the manor one morning. Mortmain knew that they would find them and sent an automaton to scare Will, warning the others to stop investigating, else he would hurt his family.
When Charlotte Branwell once again sent Ragnor Fell to investigate the Herondales, just as he did years before, fourteen-year-old Cecily found him lurking outside their home and questioned him. She immediately assumed that he was there to check on them on Will's behalf, and while she was pleased by the fact that Ragnor did not deny it, she insisted that Will should be there himself and return to them if he truly cared. To satisfy her yearning for her brother, Ragnor told her that Will misses her.
Only days after her encounter with Ragnor, Cecily decided to go to London and the Institute there, determined to return home with Will. Arriving at the London Institute, Cecily claimed that she wanted to be trained as a Shadowhunter.
Cecily went on to be trained, also guided by her own brother. It was not as she expected, however, since Will did not take her arrival very well. Aside from her frequent arguments with Will, which usually began when she tries to get him to come back or write to their parents, Cecily also found herself unexpectedly liking the Shadowhunters, whom she believed to be monsters for a long time, as well as enjoying her training, though she did not admit this until several weeks after. Cecily proved to be naturally skilled and attuned to Shadowhunting, much like Will was when he first came to the Institute.
Throughout her stay, Cecily grew to love being a Shadowhunter and being trained—something she initially refused to accept as she was intent on only staying long enough to convince Will to come home to their parents with her, or at least to get in touch with them. During one of her training sessions with Will, during which he always expressed his contempt at her being there, she struck a deal with him that if she managed to hit the target with a knife—something she has feigned not being skilled at—three times, he would write to their parents. Assuming that Cecy would not be able to, Will agreed. When Cecily succeeded, Will obliged to her request but found a loophole, saying he would write but not send it as it had not been a part of their deal, much to Cecily's irritation. Will then tells her that he will agree to sending it to them if she delivered it personally and never returned to the London Institute, and she refused.
When Gabriel Lightwood came to the Institute asking for help, Cecily, deeming herself ready after weeks of training, demanded to be a member of the party to respond to his call. With most everyone in the Institute, they traveled to the Lightwood mansion and confronted the giant, demonic worm Gabriel's father had become due to demon pox. Despite her brief training, she bravely climbed a tree in search of the giant worm and when it attacked her comrades, she jumped onto its back and stabbed it with a seraph blade. Her time at the Institute awakened her love for battle, which led to her realization that she belonged at the Institute and her decision to stay.
Eventually, Cecily and Gabriel got married and had three children, namely: Anna, Christopher, and Alexander. Cecily, Gabriel, and their sons were present when her brother, Will, died on his deathbed.
When they were young, it is believed that Will and Cecily had a good relationship, since they were siblings. When Ella dies and Will runs away from home, Cecily does not know why he chose to become a Shadowhunter when she believed they were such monsters.
When Cecily appears at the Institute, Will is furious with her and insists she go home. Cecily refuses to leave and argues with him to come home with her. She tells him that their parents are upset in losing him years ago.
Will does not seem to approve of whatever Cecily does, like when she jumped on the giant worm's back while they were battling it, or when she followed Will in search of yin fen for Jem. However, he genuinely cares for her as she does for him.
work in progress
Gabriel seemed to like Cecily when he first laid eyes on her. Will later notices their growing friendship and warns Gabriel to stay away from Cecily. Both Gabriel and Cecily are angered by this, but Will explains to Cecily that Gabriel wanted to get revenge for what Will did to his sister. Still, Cecily continues to train with Gabriel, ignoring Will's negative comments about him. They get to know each other better while training together.
work in progress
Gabriel and Cecily shared their first bonding moment when Charlotte sent them to get ingredients for Magnus in their efforts to help Jem's illness, which is when Cecily began to think of Gabriel as less of a pest, and began to enjoy his presence more. She realized that they were very similar, as both of them had done things they were not proud of, had allowed their parents' actions speak for them instead of their own, and relied on their older brothers for support. Near the end of Clockwork Princess, Gabriel and Cecily shared their first kiss after the battle against Mortmain and officially became a couple.
Personality and traits
Cecily is a fierce, strong, and brave person, an attitude she developed when she was young. She is extremely loyal, faithful, and caring to those she trusts, as well as very protective.
Typical of the Herondale Shadowhunters leading up to her, Cecily is a natural at fighting. She also has the bitter sense of humor of Herondales, and swears strongly, particularly in Welsh; as a child, she was also said to be quite demanding. Afraid of nothing, Cecily is stubborn and resistant of authority, even if what she is told to do is for her own good. She is also eager to prove herself and often charges into battle if done for those she cares about, willing to do anything, even risk herself, for them and a good cause.
Cecily is also quite a romantic, proven when she tears up while witnessing Gideon's proposal to Sophie, and how quickly she found herself falling for her eventual husband, Gabriel.
Cecily is a very beautiful young woman, with gleaming black hair and startling dark blue eyes, traits she shares with her mother and brother. She has pale skin, high cheekbones, and full lips. She is also quite small, contributing to her semblance of defenselessness, and is often assumed to be fragile and delicate, surprising people with her strength because of it.
Bearing a striking resemblance to Will, she has been described as "pretty as Will is handsome." Their similarities have been described as unnerving, as both look almost exactly like each other in their youth, particularly when both look peaceful, and even when they scowl.
Skills and abilities
- Nephilim physiology: Being Nephilim, Cecily possesses a myriad of enhanced physical and mental abilities granted to her by the blood of Raziel in her veins and also by the angelic Marks of the Gray Book. This includes enhanced strength, agility, stamina, coordination, and many others which improve over time and practice.
- Runic magic: Due to the angel Raziel's blood in their veins, all Shadowhunters are able to apply runes on their skin without any real danger. These Marks, in turn, give varied effects that serve to benefit the wearer.
- The Sight: As a Shadowhunter, Cecily is able to easily see through most magical illusions and layers of glamour over reality.
- Use of heavenly weapons: As a Nephilim, Cecily is also able to handle heavenly weapons with effect, since this would normally not work for other species. In particular, these are weapons made of adamas and forged by Iron Sisters, such as seraph blades.
- Clockwork Angel (first mention)
- Clockwork Prince (first appearance)
- Clockwork Princess
- The Whitechapel Fiend
- Nothing but Shadows (mentioned only)
- The Midnight Heir (mentioned only)
- The Last Hours (may appear)
- Cecily's necklace, given to her by Will, has been passed down the succeeding generations of the Lightwood family. It now belongs to her descendant, Isabelle Lightwood.
- According to a found family tree, Cecily died in 1945, at the age of 81, or 82.
- Cecily and Gabriel are the direct ancestors of the Lightwoods in The Mortal Instruments, namely Robert, Alec, Isabelle, and Max Lightwood.