Understanding the connections between the various creatures in the “Stranger Things” universe can be quite complex, but the link between Vecna and the Mind Flayer is relatively straightforward. Initially, Vecna was One, also known as Henry Creel (played by Jamie Campbell Bower), who was part of Dr. Brenner’s group of gifted children at Hawkins Laboratory. Henry’s malevolent nature eventually leads Eleven (Millie Bobby Brown) to banish him into an early form of the Upside Down. There, he transforms one of the existing creatures into a spider-shaped entity of pure terror, mirroring a drawing from his childhood and fueled by his fascination with spiders. Essentially, he and the Mind Flayer become two sides of the same coin.

Vecna absorbs the consciousness of anything he kills, allowing him to use its powers. Occasionally, he takes a direct approach, as seen when he implants a worm in Eleven after her victory over the Mind Flayer at the end of Season 2, draining her abilities and transferring them to himself. When Henry first entered the Upside Down, it was merely a desolate wasteland, but he transformed it into a warped version of Hawkins, shaping its creatures to serve him. Interestingly, primitive forms of the Upside Down’s creatures were already present upon his arrival.

Vecna’s control isn’t limited to the Mind Flayer alone. Demogorgons, demobats, and other creatures inhabiting the Upside Down existed before Vecna’s arrival but lacked organization or unified purpose until he intervened. Above ground, they act in concert, such that when one is killed, all are affected, attacking in cohesive formations. This is because Vecna orchestrates them from his position in the Upside Down.

Vecna aspires to remake humanity in his own likeness, which is a terrifying prospect for our heroes, given his psychopathic tendencies. His parasitic connection to those he seeks to absorb into his force only heightens the threat he poses. He continuously sends creatures to eliminate Eleven, even turning her allies against her. Although they’ve thwarted his plans several times, Vecna remains at large, and the Upside Down continues to encroach upon Hawkins. The latter half of “Stranger Things” Season 5 promises to address fans’ major unresolved questions about the Upside Down and unveil the true extent of Vecna’s abilities.