When Lucien was still a member of the Autumn Court, he fell in love with a lesser faerie, Jesminda. His father was outraged that he would want to marry someone of such low status and non High Fae-descent, which resulted in her being executed right in front of Lucien while he was being restrained by his brothers. This had a damaging effect on Lucien, who immediately left to go live with Tamlin in the Spring Court. He was later appointed as emissary for the court and in this role was sent to talk with a furious Amarantha, who tore out one of Lucien's eyes.
After the events of Under the Mountain, Lucien appears to be extremely loyal to Tamlin. When Feyre later opts to stay in Velaris, Lucien goes to search for her and attempts to return her to the Spring Court, but is inevitably unable to do so. After Elain Archeron is Made into a High Fae, a mating bond snaps into place, revealing that Elain is Lucien's mate.
Lucien Vanserra was born as the son of the Lady of the Autumn Court and Helion, but was raised as the youngest of the seven sons of Beron, the High Lord of the Autumn Court. He grew up in the Autumn Court, but never cared much about his nobility. He made friends with individuals of different courts and with individuals from non-aristocratic backgrounds. As Lucien was unlikely to become High Lord, he was allowed to roam the court as he saw fit.
During his youth, he met a Lesser Faerie called Jesminda, who lived in the countryside in the Autumn Court. She teased and seduced him until they eventually fell in love.  Beron disapproved of this relationship, as he believed it was inappropriate for a High Fae noble to marry a Lesser Faerie, and so he had her executed in front of Lucien. His two eldest brothers forced him to watch (However Eris, his eldest brother, was not there). 
After this, Lucien left the the Autumn Court and fled to the Spring Court. His brothers believed that he was a contender to the High Lord's crown, and so three of them went to kill him, to prevent him from one day becoming High Lord. Lucien killed one of the brothers, while Tamlin killed the other.
Life at the Spring Court
Now without a place at the Autumn Court, Tamlin appointed him as emissary for the Spring Court. Lucien then spent him time residing at Tamlin's court, and met with individuals from other courts, including his father Beron who he was forced to meet for political matters.
Lucien was sent to meet with Amarantha, as she desired Tamlin and wanted a relationship. Tamlin did not, and so sent Lucien as his emissary to Amarantha and keep peace in Prythian. Though after hearing that she was rejected, Amarantha refused to keep peace. In anger, Lucien told her 'to go back to the shit-hole she'd crawled out of',  and as punishment she carved out his eye and sent him back to the Spring Court. His face was left scarred from this incident.
Not long after, Amarantha hosted a masquerade Under the Mountain and claimed it was to made amends for removing Lucien's eye. The entire Spring Court attended, including Lucien, who wore a fox mask. Amarantha chose to host a masquerade so Lucien could hide the scarring, though her true motives for the party was to make Tamlin her lover and consort. However, Tamlin was outraged at the injuries that she inflicted on Lucien and so he refused and said he would rather take a human to bed. At this, Amarantha cursed the entire Spring Court to forever wear their masks, including Lucien who was forced to forever wear his fox mask. Tamlin had seven times seven years to break the curse by falling in love with a human girl who despises faeries.
Lucien is a loyal solider. At the end in Hybern, his mating bond sets in place with Elain.
After the events in Hybern, Lucien returned to the Spring Court with Feyre and Tamlin. He is skeptical of Feyre's return to the court and is desperate to see Elain, his mate, whom he only saw for moments in Hybern.
Lucien meets with Prince Dagdan and Princess Brannagh. He is sent with Feyre to escort them to the wall, so they can inspect it for weaknesses. Lucien aids them by information on the holes in the Wall, albeit reluctantly. Feyre and Lucien confide in each other about what happened during Feyre's absence from the Spring Court, though Feyre is quiet about the truth of her relationship with Rhys. 
Like most of the Spring Court, Lucien attended the Summer Solstice celebrations, though is half-asleep during one of Ianthe's performances. During the performance, Ianthe is interrupted by Feyre who glows and creates a display of light. Lucien takes her hand and kneels on the floor, adding to the dramatics of the spectacle. 
He escorts her back to her room after the celebration. During the night, Lucien's sleep is interrupted by Feyre's screaming. She knocks on his door, and he opens the door shirtless. He finds her wearing lacy clothing and in disarray. She tells him she has nightmares of Under the Mountain, and hugs Lucien for comfort. Their somewhat sensual embrace is interrupted by Tamlin, who appears angry at the situation. Feyre quickly leads Tamlin out of Lucien's room. 
Feyre and Lucien again escort Dagdan and Brannagh to the wall, however this time they visit the Continent to inspect it's wall. Brannagh is unable to winnow, and Dagdan can only winnow a few miles, and so the group winnow and hike to the continent. During their trek, three members of the Children of the Blessed approach them. Lucien rejected their plead to dwell in Prythian, though Brannagh and Dagdan are enticed by their offer. The next day, Lucien finds the three Children of the Blessed dead and their bodies mutilated.  As retribution, Lucien and Feyre sent the Bogge after the Hybern twins, though they escape unharmed. For this, both Lucien and Feyre are scolded by Tamlin, Feyre also scolded him causing his anger to unleash his magic and she purposely did not shield herself. Tamlin is motionless in shock of what he had done, while Lucien immediately comes to Feyre's aid. Later, Lucien witnesses Tamlin's brutal behaviour to one of his sentries and holds Feyre's hand to support her.
Lucien visited the Wall once again but this time with Ianthe and Tamlin and of course Feyre, Dagdan and Brannagh. In the hopes that Lucien will accept her love, Ianthe ties him in shackles so to force him to accept her sexual advances. He rejects them coldly, and is saved by Feyre who uses her Daemati abilities to force Ianthe to unshackle him.  Lucien and Feyre were discovered by Brannagh and Dagdan, and with Feyre's help they kill the Hybern twins and flee from the Spring Court and into the Autumn Court. 
Lucien and Feyre journey to the Night Court, however they are weakened by the Faebane and must travel on foot. They trek through the Autumn Court, and through the Forest House. After a few days, they are intercepted by Lucien's brothers, one of whom is Eris. They fight against the brothers and hurry quickly away. They settle in a cave, and Feyre tells Lucien about her sister, Elain. The next day, they enter the Winter Court, but are again intercepted by Lucien's brothers. Luckily, Azriel and Cassian arrive the help the pair, and fly them to the Night Court.
Though wary of the Night Court, Lucien is amazed at the peace is Velaris and comments on how there are children laughing in the street.
Due to Amarantha, the citizens of the Spring Court were forced to wear masquerade masks. Lucien wore a copper fox mask. Due to Feyre's trials, the mask was later removed.
He has one russet eye, while the other is made of a gold metal. His face is brutally scarred from his brow to his jaw, inflicted by Amarantha. His hair is red, and his skin is tanned, noticeably darker than his brothers.
Without his mask, his features are described as sharp, elegant, and ethereally handsome despite the length of scars on his face.
Lucien is sarcastic and witty, and as Alis says, needs someone to snap back at him. He covers his anguish through a bright, charismatic personality. He deeply cares for people, and is shown to be affected by things more on the inside than he lets it show on the outside.
While living in the Autumn Court, Lucien met Jesminda, a Lesser Faerie who lived in the countryside. She teased and seduced him until the pair eventually fell in love. Jesminda appreciated Lucien for who he was, instead of loving him for his noble rank. Lucien loved her with the same amount of appreciation, and even believed she was the most beautiful female he knew. The pair were not mated, though this did not diminish their love.
The pair's love was cut short, as Beron believed it was inappropriate for a High Fae noble to have a relationship with a Lesser Faerie, and so he executed Jesminda in front of Lucien. This had a harrowing effect on Lucien, who fled to the Spring Court for safety.
Lucien is bitter and cold towards Ianthe, rejecting her sexual advances. Ianthe, however, is interested in the prospect of having a child with Lucien, as their offspring would be powerful and respected. She attempts to gain his interest, but he consistently ignores her. During the night of Calanmai, Tamlin refuses to participate in the Rite, and so Lucien believes it is his duty to perform in the rite, and so sleeps with Ianthe. This night is something Lucien regrets and is deeply embarrassed about. After Ianthe kidnaps Elain and takes her to Hybern, Lucien becomes more bitter to Ianthe. He shows her no gratitude for what she has done. Despite the constant rejections, Ianthe locks him in shackles thus forcing him to accept her sexually. Lucien does not concede to her advances even after this. He is saved by Feyre, and leaves Ianthe in the Spring Court.
- The name Lucien is French and means 'light'.  Ironically, in A Court of Wings and Ruin, Lucien is revealed to be the biological son of Helion, the High Lord of the Day Court. Helion has the power to manipulate light.
- Sarah J. Maas originally planned for Lucien to have a romantic relationship with Nesta. However when she started writing A Court of Mist and Fury, Maas came to the conclusion that this relationship wouldn't work. 
Notes and references
|Characters||Rhysand · Feyre Archeron · Amren · Morrigan · Cassian · Azriel · Nesta Archeron · Elain Archeron · Lucien Vanserra · Nuala · Cerridwen · Keir · Devlon · Clotho · Madja · Bryaxis · Sevenda · Rita · Thanatos · Thanatos's daughter · Rhysand's father † · Rhysand's mother † · Rhysand's sister † · Enalius|
|Locations||Cesere · Hewn City · Palace of Bone and Salt · Palace of Thread and Jewels · Rainbow of Velaris · Restaurant · Rita's · Sidra River · The Prison · Velaris · Western Isles|
|Characters||Tamlin · Feyre Archeron (former) · Lucien Vanserra (former) · Alis (former) · Ianthe † · Andras † · Bron · Hart · Tamlin's father · Tamlin's mother · Ianthe's father · Ianthe's mother · Ianthe's sisters|
|Locations||Village · Western Forest|
|Characters||Beron Vanserra · Eris Vanserra · Lucien Vanserra (former) · Jesminda †|