Temporary Lighter

I dyed my hair dark red.
Yes, I've secretly fantasied about rangas and thought I should be one.
Amazing how many rangas are in Harry Potter.
Okay, so I have temporary dye in my hair.
I love my brown hair too much to part with it for more than 10 washes.
But I did want a change.
I'm thinking dark purple during school holidays.
Because purple wouldn't be allowed in school.
How is red a natural hair colour?
Why can't every colour be a hair colour, like animes?