Warning: possible spoilers. Read at your own risk.

In the television show version of Jessica Jones, at one point she captures Killgrave and puts him in a hermetically sealed room. She tells another character that so long as he can't breathe the same air, his powers won't work.

Placing Killgrave in the hermetically sealed room occurred one or two episodes before Killgrave's parents were discovered, and so it was before they knew that Killgrave's powers were driven by a virus.

Without any idea of the cause, he could be magic for all she knows. (All the characters on the show live in a universe connected to the Avengers movies, so they are all aware that there are super people who look and act like gods, so magic is not out of the question.) Or it could be based on line of sight from him. Or something else entirely. I didn't see anything in the series to that point that demonstrated that air was the medium through which his powers operated. Maybe I missed something?

How could she have possibly known that it would be safe to hear his voice or look at him so long as he was sealed off in a hermetically sealed room?

3 Answers 3


Jessica had a history will Kilgrave that seemed to have lasted for quite a while. In that time, she presumably paid close attention to how his powers worked. She seemed to know quite a bit about them from the very start of the show, including:

  • You had to be physically "near" him to affected
  • They only lasted ~10 hours
  • You could work around them by taking them literally

It's never explained outright, but we're lead to believe that she has figured out roughly how his powers work, though she doesn't quite understand why. (I believe early on they may have even mentioned the theory that it was pheremone based). That would include the fact that people needed to be in the same "air space" as him to be affected.

  • It seems plausible that during her time with him she could have figured it out. However, it's not an easy parameter to work out. Seeing that someone under command stops doing it after 10 hours is one thing.it's harder to imagine a circumstance where it would be clear a command wasn't working because of a lack of continuous air connection. Your answer might be as close to a narrative explanation as we'll get, but it would be nice if there was some hint given by the writers that could solidify the particular logic she used.
    – Questioner
    Commented Dec 6, 2015 at 6:17
  • 3
    I don't think it's that hard to imagine her working out that Kilgrave's powers don't work when, for example, someone can only hear him through a closed door or window. If his powers are the same as the comic book version (I haven't seen all the episodes yet), then they are due entirely to special pheromones - hence victims have to be able to inhale or otherwise absorb the pheromones for his control to take effect.
    – user22478
    Commented Dec 6, 2015 at 23:27

It was a lucky coincidence. Note that Jessica's original plan was simply to keep Kilgrave sedated while she tries to work out her next move.

Jessica Jones: I'll keep him doped up, I just need a place to stash him.

It's not until she finds out that the isolation room is hermetically sealed and soundproofed that she risks speaking to him, and even then she insists on doing it alone since she's the only person who seems to be able to resist him.

If it turned out to be control via magic (or line-of-sight or something else) then she seems reasonably confident she can resist him long enough to shock him and try something else.

  • 1
    The question isn't really about her original plan though. It's about how she knew the hermetically sealed room would be an effective barrier.
    – phantom42
    Commented Dec 5, 2015 at 15:11
  • @phantom42 - She didn't know. She guessed and happened to be right
    – Valorum
    Commented Dec 5, 2015 at 15:33
  • Every indication is that it's not a guess. At the beginning of episode 9, she tells Killgrave straight up that he can't command her because it's a hermetically sealed room, and this is before she grabbed him during his escape and realized she was immune. She acted with absolute assurance that the room sealed in his powers, and said as much.
    – Questioner
    Commented Dec 6, 2015 at 6:13
  • 1
    @Questioner - Presumably she just means "nothing gets in or out". Since she already knows that he can't command people over the phone, there must be an assumption that there's some sort of physical presence required.
    – Valorum
    Commented Dec 6, 2015 at 8:12
  • 1
    We can see how she positions herself if she felt the need to be ready to press the button by having her hand right over it when the parents first enter the room, which is completely different to her demeanor when she first listens to Killgrave. I think the evidence is clear. She is absolutely certain that his powers are transmitted through the air. The only question is how does she know.
    – Questioner
    Commented Dec 6, 2015 at 13:52

She also says that his powers don't work through a microphone. So that would mean that over the phone wouldn't work too. She knew about his powers not working over the phone because of experience so Jessica had good reason to assume that it wouldn't work from within a sealed room (over a microphone) either. I dont think her reasoning had anything to do with air, it was just that she knew that you needed to hear his voice with your own ears.

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