10 Doctor Strange Fates Worse Than Death
2. Having A Demon Encaged In Your Mind
Part of being the Master of the Mystic Arts means Doctor Strange has to go up against some seriously powerful creatures. That includes all manner of demons straight from Marvel's version of Hell, but not every demon can be returned to the pit from whence they came.
Some demons have to be handled a bit differently, so Doctor Strange has gotten creative over the years. Whenever he battles a demon he can't send back to Hell or wherever they came from, he traps them. He doesn't put them in a magical bottle or anything — he traps them in the mind of a criminal.
This isn't something he does for any demon; it's necessary for those who must be trapped within a living vessel. This is a fate worse than death for both the criminal whose mind has become the prison of an actual demon, but it's also something the demon isn't too happy about either.
When Strange does this, he finds a serial killer or murderer who is incapable of redemption and throws a demon inside their skull. Both the demon and the criminal are essentially tortured until the "vessel" dies, and the demon is blessedly returned to the pit.