Well known phrase?
I don't think that "winter is coming" is a "well known phrase". It is a trite observation. Winter is always coming, or it's here, or it's going. But it's not a famous proverb and I don't think it's a quotation and I don't think it's said unless someone sees you planting primroses in November. Which is what you're supposed to do for all that I know.
Nike trademarked "Just Do It", which is trite plus, but people are still allowed to say it.
I'm not a lawyer, but trademarks exist only in a context. So, your trademark can be a cock (Le Coq Sportif) while someone else's is (Kellogg corn flakes). The duplication doesn't lead to confusion.
In this young artist's case, I will suggest "When I am a cold woman I shall wear purple".
I am not sure about the hair but this comes to mind from the late Gerry & Sylvia Anderson.
"never explained, never alluded to"