How to keep an unnatural hair color to last?

Most don’t fade within a week. My hair is fuchsia at the moment, but I’ve had every color of the rainbow at some point or another.
Shades of blue and green fade the fastest and are the most finicky to work with. You can expect a blue or green to fade within 2 weeks and it never fades to a nice looking color.
Pinks and purples last the 2nd longest in my experience depending on the brand you use. Manic panic or ion work the best, there is another brand that Sallys sells (n’rage maybe, idk, it comes in what looks like a lotion bottle and smells like bubblegum). avoid Beyond the Zone if lasting color is your goal. They use to make good dye but they recently reformulated and now they suck. Pink and purple will last about a month or longer if you put the remaining dye into your shampoo and conditioner it will help keep the color.
After a month or 2 your roots will need to be re dyed. Btw, you will have to lighten your hair first because these none of these colors or brands will stick to natural hair!
Reds last the longest and are a huge bitch to remove, the good thing is that any brand of red will hold fantastically.
Yellow and oranges are hard for almost anyone to pull off.

Be aware that no matter what brand you choose, there is always the possibility of the dye rubbing off on anything that touches your hair. Towels, sheets, clothes….everything and it will happen mostly when your hair is wet. Watch out for rain and absolutely no swimming underwater.
ALWAYS wash your hair with Luke warm or cold water. Hot water will suck out the color faster.

@cheebdragon Okay, thank you! This is really helpful :) I’ve had a tiny bit of bright red in my hair and I remember having it for a while, and when it faded it didn’t long too bad (I don’t know what that color would look like on my entire head though). I think a dark purple or a dark color in general would look better on me anyway.

Unfortunately though, my parents won’t let me get my hair dyed an unnatural color because yeah, I’ll have to bleach it first and that will kill my hair, plus my dad is pretty traditional and doesn’t like hair like that. Have any ways I can convince them to let me do it? I really want to do something cool and different with my hair.

What color is you hair naturally?
You don’t have to bleach it, you can use a box of blond hair dye from the grocery store, it’s not very damaging and you can wash it out as as soon as your hair starts to lighten. Even if your hair is naturally dark you can select a lighter shade of you color (Id say 2 or 3 shades lighter would be enough), It just needs to be dyed for it to stick to. A purple over a light brown (especially the darker purple of manic panic) would end up being pretty subtle under most lights but the purple would really shine in the sunlight.

If your hair is naturally light in color, you should avoid doing a darker shade of purple because when your roots grow out it will make your hair look a lot thinner.

@cheebdragon My natural hair is a chestnut brown color, but right now it’s darker brown with faded red highlights because I dyed it back in summer. That’s why I want to do a darker shade, because it goes better with my looks than a light color does. My hair stylist said that it won’t show up as much if I don’t dye it lighter first. And okay, that sounds good!