HELLOES.
I have really light hair naturally and I recently dyed it blue; it turned that grey/green/blue colour you can get after a while. I bleached it but now the yellow has come out weirdly dark in like the middle of the back of my head. Thoughts? That's not the big issue though:
I also keep trying to dye the front of my hair black and it keeps going this weird maroonypurple colour. I liked it when it first happened but I really want black now and the yellow with it makes me look like an ad for cadbury's. So yeah, WHY IS THIS HAPPENING? I looked through all the forums and couldn't find anyone else having the same problem. I've tried two different dyes: Directions and Stargazer, and I'm planning on getting a more mainstream one like Loreal or whatever, but I don't want to fork out the money if it's going to do the same thing...

i know i had a problem getting schwarzkopf black dye to hold in my hair but i dont have experience with any of the other products

If you don't mind something very permanent, Clairol Hydrience in Black Pearl is great.
I applied it over bleached hair and it didn't fade at all.
Also, I haven't used Nice 'N Easy Black but that's supposed to be pretty good as well.

I just dyed some of my very bleached hair black. First I used Majirel (one of L'Oreal's professional lines) and it washed out brown pretty quickly. Next I did L'Oreal Preference which has lasted much longer. Will be trying Nice N Easy again next. I'd say go for a mainstream brand, Clairol is my favourite. They're good because they're formulated for mass consumption so are harder to mess up

As for the colour going at the back of your head, mine used to do that. I figured it was a combination of it rubbing off on my pillow at night and standing in the shower too long with the water hitting the back of my head.
You just need to redye more often but if it's coming through very yellow it might be that it needs bleached just a shade lighter. What directions and stargazer colours are you using?

Yeah I think I just need to bleach the back again.
I put blue over the maroon-type colour that was at the front and it's gone dark purple. Where the colours have all mixed in the middle between the yellow and the purpley colour, it's gone black, so I'm going to have a fiddle with dying the purple different colours that I already have to save money.
Thanks for your help!

It still looks cool anyway.