Lucian Kiggs is the illegitimate prince of Goredd and the fiancé of his cousin, Princess Glisselda. After the investigation to find the murdered prince's killer begins, there is tension between Seraphina Dombegh and Lucian. Notably, she asks him, "What's it like being a bastard?" However, this tension quickly grows romantic.
Lucian's mother was Princess Laurel, the youngest daughter of Queen Lavonda of Goredd. At fifteen, she eloped with a Samsamese admiral, with whom she later had Lucian. When he was five, Dame Okra Carmine convinced his parents to allow her to take Lucian to meet his grandmother while they left on a sea voyage; his parents perished on the trip, and Lucian joined his Goreddi family.
He initially had trouble fitting in, as he spoke little Goreddi and was a troublemaker at heart, often picking fights, stealing, and intentionally embarrassing his royal family. However, Prince Rufus eventually took Lucian under his wing, and over the course of months Lucian's behavior improved. Rufus saw that Lucian needed a purpose in his life, and convinced Lucian to pray to St. Clare; Lucian did so, and even promised St. Clare to always speak the truth if his prayers were answered.
At age nine, Lucian accompanied Rufus to the wedding of Claude Dombegh. Upon hearing Seraphina Dombegh sing, he had an epiphany that Seraphina embodied truth, and that it was his calling to search for truth by becoming an investigator.
Kiggs was devastated by his uncle Rufus's death as if Rufus had been his own father. He was astonished by her skills when he heard Seraphina play the flute solo at the Invocation for prince Rufus's funeral, although having heard from Glisselda about Seraphina. Shortly after Rufus's burial, Kiggs was called away to deal with a mob of Sons of St. Ogdo attacking a newskin saarantras, Basind. Kiggs encountered Seraphina there and expressed his admiration for her music. He also deduced that Orma, Seraphina's music teacher, is a "stealth scholar" or a saarantras exempted from having to wear the silver bell.
Kiggs' men brought in some of the attackers they caught. Seraphina mentioned that she saw two men jump over the bridge but heard only one splash; they checked under the bridge and caught another Son of St. Ogdo. Kiggs was impressed with Seraphina's observational skills, but the arrival of Undersecretary Eskar distracted him.
Eskar and Kiggs got into an argument. Eskar insisted that the Guard did not provide sufficient security for saarantrai, considering the fact that Ardmagar Comonot is scheduled to visit in ten days, while Kiggs pointed out that there was understandable unrest due to Rufus's murder. After Eskar leaves, Kiggs tried to return his conversation with Seraphina, but she rebuffs him and left to join Orma. Kiggs led his men away.
At Glisselda's soiree eight days before Comonot's visit, Kiggs overheard Seraphina suggesting that Sons of St. Ogdo murdered Prince Rufus in a draconian fashion to stir up dracophobia. When Earl Josef treated her idea contemptuously, Kiggs stepped in and lent his support to Seraphina by agreeing with her. He quoted Pontheus to Josef and Seraphina recognized it, impressing Kiggs. As Kiggs argued with Josef, Queen Lavonda arrived; seeing Seraphina, distracted, standing in the Queen's way, Kiggs pulls her away. As the Queen scolded Glisselda, Kiggs hoped that Glisselda would be able to fulfill her duty to the saarantrai.
Kiggs later joined Glisselda when she called him over to talk to Seraphina. Glisselda openly referred to "dragon affairs" within earshot of the saarantrai, making Kiggs uncomfortable, but he didn't point out her rudeness. When Seraphina called Glisselda out on it instead, he was relieved and impressed, and also willing to make the first move to demonstrate acceptance of the saarantrai by asking Eskar to dance. Glisselda tactlessly tells Seraphina that Kiggs is good at this sort of thing because he's a bastard, offending Kiggs, but he keeps his discomfort to himself.
When Kiggs finds Seraphina sneaking around in his name he confronts her and talks to her. She tells him about Imlann and Sir James, and he decides to go with her in search of Sir James.
He may be a prince, but he is also a bastard, and as a result, shares Seraphina Dombegh's feelings of being an outcast. He is also very perceptive, making Seraphina very self-conscious about him finding out the truth.
Lucian is Glisselda's cousin, as well as fiancé. He is naturally on good terms with her, and can be quite protective of her when needed be. In return, Glisselda cares for him and displays a sisterly attitude towards him at times. The two, along with Seraphina, become a sort of investigational trio.
While initially on fair terms with each other, Lucian and Seraphina begin to fall in love over the course of the story, developing a close relationship in the process. He often tries to engage in conversation with her during early events in the book, having been impressed by her musical talent (which she demonstrates after playing the Invocation at Prince Rufus's funeral), although Seraphina is wary of him, and mistakenly lashes out at him after he inadvertently presses her in a talk involving her mother. Following this, he does not speak to her until she apologizes. The two later interact at the Blue Salon, and Lucian becomes fascinated by Seraphina's wit and intelligence, though she continues to avoid him in a natural manner, fearing that he may discover her secret if they become too close. During the ball celebrating the Ardmagar's arrival in Goredd, Lucian dances with Seraphina, and they formulate a plan to investigate the mystery of Prince Rufus's death, bringing them even closer together as friends.