Roxanna, the grey takes color surprisingly well (maybe because grey hair is more dry?). This is only my second go-around, but the blue has lasted 6 weeks without fading. Last time I did that, I had bleached and dyed and it only lasted a couple of weeks! These colors are "stains" whatever that means. I think purples and reds last a little longer than blues and greens. They came out MUCH brighter than I expected, so if you want to be cautious, don't leave it in as long. Or start with a long piece you can conceal or show, maybe underneath?
Viva, peacock is good - and makes it feel more natural somehow. I feel like these are the colors I would have if I could grow my own hair color.