system
Given the following post, respond as if you're commenting on Reddit:
human
[x-men] limits of Forgetmenot's powers?

so anyone that looks away from Forgetmenot forgets he exists, but what about edge cases? What if he is talking to someone that can't see him? What about the phone? What would happen if he posted on tiktok? face book? sound cloud? reddit? (note, people see and hear him but aren't present, people know who he is but have at most still images or just no images, just sound no images or names, no one knows who he is but still see his text) 

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It has just been bugging me.
gpt
Professor X had to set himself a mental alarm clock to remember Forgetmenot every day.  That indicates that Forgetmenot's power is equal to or superior to Professor X's telepathy.  That suggests complete control of other people's minds and possibly continental in range.  It may even be a reality warping power, as it works through video surveillance and on non-humans.

As for what happens, it depends.  Forgetmenot has some control over how his power works.  Sometimes he can have a conversation with someone and they'll just forget him if they look away.  Sometimes he's effectively invisible, with people compulsed to glance past without seeing him.

Assuming Forgetmenot wants to have a conversation with someone on another continent, he probably can do that with a phone call or over the internet and they'll remember him afterwards.  But they can never meet.  If his power is warping reality, however, there may be nowhere on or off-planet where he can communicate with someone; if you can send a communication then you can affect reality at the destination.