A. Indigo has an illness that drains all the color out of her body. It's called "palette puncture". It even affects what she's wearing. Indigo doesn't trust modern medicine and only uses a kooky old-fashioned treatment that STEALS hues from others. Theirs grow back, because their palettes are healthy -- it's still a serious crime.
Heavens! But there are palette patches at the drugstore!
Indigo's giga-hippie parents raised her to only ingest or apply things found in forests inside hollow logs.
Q. How's this treatment work?
A. You think I'm going to give you instructions for an illegal ritual?! Sure thing! It's illusion-school principles applied to an earth-school methodology. You use a handwand (or equivalent) to apply vacuum ink, which has to be fully homeopathized, to a charged matrix, perform a standard property absquatulation as if you're the ink, and parge the pigments to your dermis. It keeps for a few weeks; then your rotellae cycle it pastward.
Even consensual use is illegal because homeopathy is impossible without taking away matter from other universes -- god knows what you could be doing to someone. And if v-ink's allopathic, it doesn't matter HOW charged the matrix is, you're not absquatulating shit!
Q. Does she ever ask people if she can have their colors?
A. No.
Q. How long has she been doing this?
A. Since she realized her students tend to tolerate it.