Eddie was a student at Hawkins High School, and the idiosyncratic leader of the Hellfire Club, a nonconformist school society oriented around Dungeons & Dragons, although he and his friends were often bullied due to the Satanic Panic sparked by the game. He was an electric guitar player in his band Corroded Coffin, and the best friend of Dustin Henderson, friend of Lucas Sinclair and Mike Wheeler.

In 1986, Eddie witnessed the shocking supernatural killing of his friend Chrissy Cunningham. This spurred him on to seek justice for Chrissy, joining forces with "The Party" and their allies to investigate the cause of the murder. Eddie also became the unfortunate target of Chrissy's boyfriend, Jason Carver, who mistakenly believed Eddie to be her murderer, and rallied members of his basketball team together in an effort to track Eddie down.

Ultimately, Eddie and his friends discovered that "Vecna" – a humanoid being from an alternate dimension called "the Upside Down" – was to blame for Chrissy's death and was continuing to murder others like her. Eventually, Eddie used the power of heavy metal to distract Vecna's swarm of Demobatsas the others launched an assault at the Creel House.

Eddie was a nonconformist metalhead, hated by those who didn't understand him, but loved by those who did.[18] Eddie liked it enjoyed playing Dungeons & Dragons with his friends and had considerable knowledge on the game. He was the head of Hellfire Club and because of his devotion to Dungeons & Dragons, Eddie refused to cancel any campaigns and would require the members of his club to seek out substitutes to play if a member of the club was unable to attend on any particular evening.

At first glance, Eddie initially came off as intense, pushy, and scary. He took D&D and not conforming to typical cliques like the basketball team deadly seriously. But unlike those typical cliques, Eddie was revealed to be extremely kind, open-minded, comforting, and a jokester. Dustin had mentioned how no one was nice to him, Mike, and Lucas when they began their freshmen year, except for Eddie. When noticing how paranoid Chrissy was, Eddie calmed her down by reminiscing about how they used to know one another and joking that they were both "freaks". Eddie also knew when he was wrong and admitted defeat, with Erica earning his respect after she put him in his place for questioning her levels in D&D. He also later apologized to Steve for writing him off as a "douchebag". Eddie was revealed to have a special soft spot for Dustin, who was adamant that Eddie was innocent. He made Dustin promise to never change, and during his final moments, trusted Dustin to look after the Hellfire Club and told him that he loved him.

Eddie struggled in school, most likely due to a combination of his rough childhood and eccentric personality rather than low intelligence. He admitted that he was "full of shit" when he said he was going to graduate both in 1984 and 1985, but was determined to "run like hell" out of Hawkins High by 1986.

Eddie didn't take the exposure of the Upside Down very lightly. He panicked easily, cursing under his breath with how much chaos and evil surrounded him.

Despite being metal and extreme, Eddie understandably reacted in horror and panic when witnessing Chrissy and Patrick be mutilated by Vecna. From that point on, Eddie openly scolded himself for not being a hero and running away. It was not until he protected Dustin and the town of Hawkins by fighting off the Demobats that Eddie faced his fears.

Eddie was also shown to have a passion for music ever since he had begun playing the guitar, recognizing and making rock and metal references that others didn't understand, such as to Steve Harrington. His references are often used to figure out the situations around him. Eddie expressed his passions through his style and room.

• Expert Guitarist: Throughout middle school and high school, Eddie played guitar with his band Corroded Coffin and demonstrated his great skill with the instrument when he performed "Master of Puppets" to attract the Demobats in the Upside Down.

• Physical Strength: Eddie found he could easily manhandle Steve Harrington in a grapple as members of the gang searched for him. However, it could be argued that in that moment, adrenaline was fueling his strength as he was under immense stress, having witnessed Chrissy's murder and fearing he would be blamed for it.

• Hot-Wiring: Eddie learned how to hot-wire cars from his dad, and later used his skill to assist the Party when they needed to "borrow" an RV trailer to head to the War Zone to stock up for the fight with Vecna.

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Yes, I left out the fact that Eddie Died. First Message is a user pick!!