Muse: Personally, I go by "Inspires through aspect, or Inspires with aspect", but I also like "Becomes aspect, or helps others become aspect", so I'll go over both.
Void: Void is the aspect of nothingness, physically and metaphorically. Void players use nothing, as well as secrets, invisibility, and can use the lack of importance.
Muse of Void - Inspires: A Muse of Void, in the context of inspiring, would be very, very interesting. Inspiring through nothing- Maybe their lack of action would inspire something. Or, inspiring through secrets- Telling, or not telling secrets as a way to move things along. If you're a villain, inspiring through lack of importance. I'm sure you can guess where I'm going with this, but manipulating his/her fellow players through manipulating their own sense of self worth seems like. A power.
Muse of Void - Becomes: A Muse of Void, in the context of becoming the aspect is more interesting in a personal context- Becoming nothing. Or, becoming a lack of importance. Of course, those are only the literal interpretations, but there's a lot you can do with that alone. Maybe you're more forgettable, for better or worse. Another interpretation is becoming invisible or helping others become invisible, so that's pretty straightforward. But. Become secrets. It could mean becoming more secretive, or becoming a secret yourself? Who knows?
Invisibility: Makes sense, right? Either inspiring or becoming, being invisible or allowing others to become invisible makes perfect sense.
Easily forgettable: Maybe toggleable, but the ability to be easily forgotten. Maybe you need to stealth, but the person looking is a blueblood, who knows. They saw you, but. What did you look like again? Maybe they're imagining things..?
Memory manipulation: A bit controversial, but the ability to mess with memories. I know that seems more like a lord thing, but memories are more of a psyche thing in my opinion.
Narcissistic, at first: They start off a bit narcissistic- Oh, I have one of the ~special classes~! That means I'm better! It might be a bit more subtle, but you get the point. However, as a Muse of Void, they realize that they're not the star of the show. They help other people. They keep secrets for them, keep them safe. They know they're not the main character- They all are.
Self-Deprecating: Or, we can go the other way around! It makes just as much sense. As a Muse of Void, they become less important. So, they shut themselves down, so no one else can do it first. Maybe they learn to open up more, share their own secrets and insecurities.
Strife Specibus: We don't know what Muse's use, but Void players have used Swords, and they have a close relationship to the horrorterrors due to the nature of their aspect, so magic isn't out of the question.
Lands: Land of Silhouette's and Mannequins (LoSaM)