Erica

Erica Sinclair (portrayed by Priah Ferguson) is Sue and Charles Sinclair's youngest child and is Lucas' younger sister. Introduced in the second season as a recurring character, she was promoted to series regular in the third season. She aids Dustin, Steve, and Robin in infiltrating the Russian base beneath Starcourt Mall. During these events, Dustin convinces Erica that, like himself and his friends, she is a nerd and that she should embrace that. At the end of the third season, she is given Will's Dungeons & Dragons manuals. She is very snarky, foul-mouthed, sassy and often thinks of Lucas and his friends as nerds, though she can also be nice at times. In season four, she has embraced her nerdy side and joins the Hawkins High School's Hellfire Club in her brother's place after demonstrating proficient knowledge of Dungeons & Dragons. She serves as a lookout and communicator between the many groups in their plan to defeat Vecna.