One of the most popular theories circulating on social media since season 4 is that Eddie will return in season 5 as Kas the Bloody Handed. He is a D&D character like the villain Vecna and is a vampire who follows Vecna before ultimately betraying him. It is a wild theory.
However, a fan has made this theory even wilder by saying that Max will be Kas, not Eddie. The theory says that Eleven (along with Brenner, who takes this theory into the stratosphere of wildness) will train Max so that she can kill Vecna just as Kas does.
We know Kas sacrificed himself to Vecna to become half-empire. He was Vecna’s trusted soldier, but after years and years of imprisonment; he broke his trust and started a war against his master. Just like in Stranger Things, Max offered her dark secrets to the devil, in order to distract him. However, things didn’t go according to plan, and she ended up in a coma. Now, there is a strong possibility that Max’s soul is alive in the Upside Down and she, along with Eleven, is planning a massive war against Vecna.
Redditor DrPepperNChill wrote this theory.
"I know everyone wants Eddie to come back, but unfortunately, he is gone. Sorry If you all remember, at the end of Season 4 Eleven tries to find Max in her mind, but she can't. This tells me that Vecna has already started to take over, and is beginning the "resurrection" process.
I understand that Max is not clinically dead, however we also know that the use of DnD in the story is loosely based. It's more of a way for the characters to identify the bad guy, and find ways to possibly destroy them. Knowing this it would make sense that Vecna could then use his power to resurrect her through her mind, similar to how Billy was controlled. In the end Eleven, through the help of Brenner (you really think he's dead 0.o) will complete her training so she is strong enough to free Max, allowing her to kill Vecna just as Kas did."
Fans will remain hopeful that it is Joseph Quinn's Eddie who returns as Kas if Kas is to play a role, though. What are your thoughts on this wild theory? Let us know in the comments section.