Lucas was the son of Mr. and Mrs. Sinclair, living with them in Hawkins, Indiana. He was best friends with Mike Wheeler and Will Byers from a young age. In grade four, Dustin Henderson arrived at their school and joined their friend group. They would often gather at Mike's house to play Dungeons & Dragons; this hobby was developed as early as 1979. The four boys had a great relationship with their science teacher Mr. Clarke, and they were members in the AV Club he ran. They would take part in the annual science fair, winning almost every year.
On the evening of November 6th, 1983, Lucas, Dustin, Mike, and Will played Dungeons & Dragons in Mike's basement. Mike, acting as Dungeon Master, summoned a Demogorgon, which ultimately defeated Will's character. While they looked for missing dice, Mike's mother Karen insisted it was time for his friends to leave; shortly after this, Lucas, Dustin and Will cycled home.
The next day, Will did not show up to school, which perplexed Lucas, Mike and Dustin. As they played with Mr Clarke's newly delivered Heathkit, they were summoned by Principal Coleman to talk with Police Chief Hopper. Hopper confirmed to the boys that Will was missing, and asked about Will's way home the previous night.
The boys investigated their friend's disappearance that evening and accidentally encountered the escaped Eleven, who they allowed to stay in Mike's basement, making a pillow fort for her to sleep in.
Lucas and Dustin noticed Mike wasn't at school, since he was at home to accommodate El. After school, Dustin and Lucas came to Mike's house, discussing Eleven and what could have happened to Will. Lucas said that they should tell Karen about Eleven, but El used her telekinesis to prevent him from opening the door to leave. Later that evening, El attempted to explain Will's situation; she flipped their Dungeons & Dragons board upside down, on top of which she placed Will's player piece and then the Demogorgon piece. This gave Lucas, Mike and Dustin a vital clue as they continued to theorize about what happened to Will.
Lucas, Mike, Dustin, and El commenced "Operation Mirkwood", where El led them through the woods to find evidence relating to Will. They eventually arrived outside the Byers household, where El said Will was hiding. This statement confused the three boys. After seeing police cars race by, they followed in pursuit on their bikes. They saw what appeared to be Will's corpse being dragged out of the local quarry; this lead the boys to feel distraught and angry with Eleven, who they believed was lying.
After El tampered with Mike's radio to project the sound of Will quietly singing, Mike decided to show this to Lucas and Dustin, who wondered if Will had become a ghost. After further discussion the boys theorized that Will was stuck in the Vale of Shadows, a "dark echo" dimension of death and decay, which El labeled the Upside Down.
They decided to bring El to their school so she could use the Heathkit to communicate with Will, which was much more powerful than the boy's portable radios. Mr. Clarke told the group that they had to attend an assembly for Will's death before they could use the radio. During the assembly, the bully Troy made crude jokes about Will, which angered Mike and lead him to confront him after the assembly. Troy attempted to hit Mike, but Eleven froze him in place and made him urinate on himself using biokinesis, much to the amusement of the boys and their classmates. They continued to the Heathkit. With El tapping into the device, they overheard Will talking to his mother through a temporary portal to the Upside Down - however the radio overheated and caught on fire.
At Will's funeral, the boys discussed the possibility of alternate dimensions with Mr. Clarke. He described scientific ideas and concepts, utilizing the metaphor of the flea and the acrobat. He mentioned that a gate between dimensions would have adverse affects on the electromagnetic field in their dimension. Later that day, Dustin experimented with a compass, noticing that the needle did not point towards true north, and the boys guessed that there must be a gate nearby influencing the electromagnetic field, like Mr. Clarke had said.
The group followed their compasses, believing if they went 'North', they would be lead to the Gate. However, Eleven was manipulating the electromagnetic field for the boys' safety because she considered it too dangerous to enter the Upside Down. When the boys realized that El had been doing this, they argued about her; Mike was more sympathetic and trusted her, while Lucas was critical of her help. The two boys ended up fighting; Eleven used her powers to push Lucas off Mike and into the air, injuring him. This angered Mike and left El upset, who vanished from the scene.
A rift grew between Lucas and the two other boys, who continued to argue about Eleven. Lucas attempted to once again find the Gate while Mike and Dustin searched for El.
Lucas used his compass, following the needle. He eventually arrived at Hawkins National Laboratory; he was unable to pass the wire fence surrounding the laboratory. After climbing a tree, he used binoculars to watch over the laboratory grounds, and he saw that multiple vehicles were setting off towards the suburbs of Hawkins. Realising Mike and Dustin could be endangered, Lucas informed his friends that 'the bad men are coming'. He climbed down from the tree and began to cycle as he continued to co-ordinate with his friends over radio, until they were cycling together through the suburbs. Eleven, who had been found by Mike and Dustin and riding on the back of Mike's bicycle, used her abilities to prevent them from harm.
The group reached a deserted field, where Lucas, Mike and El reconciled. After they realised the laboratory was still looking for them, they hid in an abandoned bus. Chief Hopper found them, taking them to the Byers household to meet with Joyce, Jonathan and Nancy. Together they broke into the middle school, creating a makeshift sensory deprivation tank which El could use to enhance her psychic abilities. They learned that Will was alive, barely surviving in the Upside Down.
While Hopper and Joyce infiltrated the laboratory and Nancy and Jonathan set a trap for the Monster, the four kids remained at the school.
As part of an "agreement" with Dr. Brenner to gain passage through the Gate, Hopper revealed El and the boys' location to laboratory officials. Agents broke into the school, capturing El and the boys. Eleven killed most of the agents, using biokinesis to make them bleed to death, however, this "drained" her of energy and strength, causing her to collapse. Without her protection they were recaptured; but the Monster, attracted by pools of blood spilling from dead bodies, burst through the school wall via a temporary portal. The surviving agents were understandably distracted, releasing El and the boys, and they ran in panic to Mr Clarke's classroom. The Monster breaked in, almost killing them. El intervened, using biokinesis to pin the Monster against a wall, while also immobilising Mike to prevent his intervention. El looked back at her friends, telling Mike goodbye before turning to face the Monster. She used her last remaining power to disintergrate the Monster, a process which appeared to make herself also disintergrate. The boys frantically looked for her in the classroom, but she was gone.
One month later, on Christmas Eve, the four boys once again played Dungeons & Dragons. This time, Mike summoned the Thessalhydra, but his friends' characters triumphed over the enemy.
"Would you shut up about Lando?!"
"Everything I said about you being a traitor and stuff, I was wrong. I'm sorry."
"Do you hear me?! The bad men are coming!"
- In the Montauk pilot script, Lucas's original surname was Conley.
- When playing Dungeons & Dragons he plays as a Knight.
|Season One appearances|
|The Vanishing of Will Byers||The Weirdo on Maple Street||Holly, Jolly||The Body|
|The Flea and the Acrobat||The Monster||The Bathtub||The Upside Down|