The Exorcist : i wonder if the gemini killer will be cannon if a season 2 happens

well since this series is a kind of true sequel to the first movie and since ignoring the events of the heretic, I wonder if they are going to make exorcist 3 or just legion cannon if a season 2 happened and if so I wonder if they are going to make the gemini killer cannon

Well the legion storyline with the gemini killer wrapped itself up in Exorcist III.

I don't know how they would continue it, but if they can then more power to them.

Exorcist III was actually pretty good and it would be pretty damn funny if the show took the same stance as most fans - ignore the Heretic and only acknowledge Part III the superior sequel as canon.

Legion and The Ninth Configuration are canon to The Exorcist as they were penned by William Peter Blatty. This, while admitting a good show, is not canon to the movie as it is not penned nor directed by Blatty.

In Legion/Exorcist III, the demon placed the soul of a serial killer into the corpse of Karras as a revenge. If the entity had free range all that time, how could have it taken four decades to get to Regan once again? That's a retcon right there. I wouldn't be surprised if they switched up more elements involving Karras. I just wish they would acknowledge him by name!