|“||You can't spell America without Erica.||”|
–Erica Sinclair, July 2 1985
During the summer of 1985, Erica would help Dustin Henderson, Steve Harrington, and Robin Buckley in discovering a secret Russian base underneath Hawkins's new Starcourt Mall. When discovering the Russians were opening a portal to another dimension, Erica would learn her older brother and his friends had dealt with this kind of activity in the past two years. As Erica helps Dustin, she would reveal herself to be a nerd and is encouraged by Dustin to embrace it, instead of despising it. After escaping the Russian base, Erica met up with Lucas and continued to help him and his friends in stopping the Mind Flayer.
On the morning of October 31, Erica watched as Mrs. Sinclair photographed Lucas in his Ghostbusters costume. She taunted him, calling him a “nerd”.
Erica was having breakfast with the rest of her family when Lucas asked their father for advice. Later, when Dustin was trying to contact his friends to warn them about Dart, Erica, who had sneaked into Lucas's room, was the only one to answer him. Dustin tried to explain to her the severity of the situation, however, Erica didn't listen and turned the radio off.
The next day, Erica was playing in her room when Lucas came to retrieve his toy she had taken from him. It was then that she finally revealed to Lucas that Dustin had been trying to contact him.
On the night of June 29th, Erica was hanging out with her friends at the new Starcourt Mall. When Lucas, Mike, Will, and Max arrived to sneak in to see the new George Romero movie, Erica traded insults with her brother as they walked by.
On July 2nd, Dustin, Steve, and Robin attempted to convince Erica to crawl through a series of air ducts connecting to a storage room allegedly holding Soviet equipment. Erica agreed to do so, but only on the condition that she receives free ice cream for life. Erica succeeded in accessing the storage room and opened the door for Dustin, Steve, and Robin, where they found mysterious, green substances encased in glass containers. Moments after, the room was revealed to be an elevator and began descending rapidly.
Erica is the somewhat typical annoying and little sister to Lucas and a source of irritation to him. She constantly calls him weird and annoying due to his nerdiness and for the same reason isn't fond of Lucas' friends, thus barely showing any respect to them. However, despite her abject disapproval of nerds, she later reveals that she is a math whiz and therefore a nerd herself. It's also implied she sneaks into his room and steals his stuff, such as Lucas' He-Man action figure. Additionally, while she does not doubt the existence of the Upside Down and the creatures that come from it after Dustin explains them to her, she initially refused to believe that Lucas was involved with either of them until he helped save her from the Russians. She is also incredibly self-centered, choosing to help Dustin, Steve and Robin infiltrate the Russian base beneath Starcourt Mall with the promise of free ice cream and protecting capitalism rather than out of patriotism.
Erica seems to have a good relationship with her mother though she does criticize Erica for teasing her brother and eating too much junk food.
Although not much interaction is shown between the two of them, Erica is implied to have a good relationship with her dad.
Erica would taunt her older brother Lucas and annoy him, becoming a source of irritation for him. In 1985, when Erica learned about Lucas and his friends' encounters with the Upside Down and its monsters, she did not believe that Lucas was involved in any of it despite believing everything that happened. That changed, however, when Lucas came to her rescue at Starcourt Mall. Though Erica still annoyed Lucas, the two worked together in defeating the Mind Flayer and closing the Gate. Three months later, Erica was given all of her brother's and friends' D&D set which she accepted; hinting the two would grow a better relationship with each other.
Erica was very dismissal to her older brother's friends, including Dustin Henderson. When Dustin tried to get in touch with Lucas to inform him about D'Artagnan, Erica did not bother to help Dustin and turned off Lucas's Supercom.
However, in 1985, they soon formed a friendship when Dustin requested Erica's help in discovering a secret Russian base underneath Starcourt Mall. Erica did not bother believing Dustin about Upside Down and its monsters, despite not believing her brother to have witnessed all of it. When Dustin found out Erica was a nerd, Dustin would playfully call her a nerd, much to her annoyance as he slowly convinced her to accept it. The two worked together in rescuing Steve and Robin from the Russians and then protecting and caring for them after they were drugged with truth serum. Erica did not believe the existence of Dustin's girlfriend, Suzie until he confirmed her existence by contacting on Cerebro. As Dustin and Suzie sang Neverending Story, Erica was shocked and out of annoyance, ended their transmission after Suzie gave out Planck's constant and the two started expressing their love for each other. Three months later, Erica is shown to still be on friendlier terms with Dustin as she was given the Party's D&D sets.
After the opening of Starcourt Mall, Erica became a frequent customer at Scoops Ahoy where she kept asking for samples of different flavors of ice cream, much to the annoyance of Scoops Ahoy employee, Robin Buckley. When Dustin couldn't fit into the air vents to get to the secret room at the mall guarded by the Russians, Erica was asked by Robin to help them as she was small enough to fit through the vents. Erica, agreed to help, on the condition that she gets free ice cream for life, which Robin accepted. As Erica climbed through the vent, Robin guided Erica to the secret room and seemed relieved when Erica made it out of the vent and entered the room safe and sound. When trapped in the secret Russian base underneath Starcourt, Robin helped Erica and Dustin escape when they were spotted by Russians, leaving Robin and Steve to be captured. However, Erica and Dustin managed to come to Robin and Steve's rescue and escape the base together, as they protecting the older teens as they were drugged with truth serum until they were cured. Both Robin and Erica continued to work together in helping stop the Mind Flayer.
|Season Two appearances|
|Trick or Treat, Freak|| |
| ||Dig Dug||The Spy|
| || ||The Gate|
|Season Three appearances|
|Suzie, Do You Copy?||The Mall Rats||The Case of the Missing Lifeguard||The Sauna Test|
|The Flayed||E Pluribus Unum||The Bite||The Battle of Starcourt|
|Mr. Sinclair||Mrs. Sinclair|
- Erica is a fan of My Little Pony, which Dustin says is nerdy and confirms Erica's secret nerd status.
- Erica is the second youngest sister of a member of the Party; after Holly Wheeler. However, Erica is older than Holly and learned about the Upside Down and its inhabitants while Holly noticed them, but was ignored.
- Erica became the second main character to be black skinned after her brother when she joined the main cast in Season 3.
|For this subject's gallery, see Erica Sinclair/Gallery.|