[@Rhiannon]
Here is my idea.

My idea for the Invisible People is more like a very powerful curse that is cast by either extremely powerful witches, demons, and things that lurk on the edge of reality. The whole entire thing boils down to the victim being stripped of pretty much everything they are and cease to exist. Obviously this is incredibly fatal to pretty much everyone, everyone except for witches who substitute most of their magic to cling to life. This leaves them with a body that cannot be seen, complete memory loss, and everyone else losing their memories of the victim as well. The victims are called "The Eaten" as the only thing they have left are scraps of magic that survived the ordeal.

The only "good" thing about being a member of the Eaten is that, well... you're permanently invisible and you live a long time. The exact numbers aren't known because there are no known records of an Eaten dying of old age, with most "Lying Down" and fading into the ether sometime in their lifetimes. The oldest Eaten on record was 79 before Lying Down. There are about several dozen Eaten in the world at any given time as the power needed to cast the curse is immense, the knowledge on how to cast the spell is sparse, and it always brings attention to the caster.

Dealing with their condition is up to the individual Eaten, but many take to applying vast amounts of makeup or wrapping themselves in bandages to give themselves the illusion of existing.
[hr]
In all honesty I just wanted to play a punk Invisible Man who goes out on the down doing mischief and occasional vigilantism along with existential dread.

EDIT: So I just got my killer idea, the reason why you can't see The Eaten is because if you did you'd be able to match faces with memories and that would be counterproductive to the curse. So it's not like they are actually invisible, it's just that the curse doesn't let anyone see them.