His hair looks to have suffered from over-use of heat with dark hair dye. The heat from straighteners on the ends of hair that's been dyed multiple times cause the molecules to be fixed within the core of the hair, and the longer the hair the more the dark pigments build up but never fade and this is exacerbated by silicones in shine products or hair colours that promise shine. When he retouches his roots the permenant colour has to slightly lift out his own pigment and add the new colour and it's difficult to replicate the colour that's now very dark at the ends. Sometimes people with naturally dark brown hair dying it a very similar colour to their own can get "hot roots" where the dye has lifted their roots to reveal red tones but the added pigment isn't strong enough or left on long enough to reach the desired dark brown. It shocks brunettes who then try to remove the colour with a product like ColourB4* to find it's unable to release dark pigments at the ends but the roots and lengths show a dodgy orange. If this happens the only solution would be to cut off the dark ends and then the dodgy ginger hair should take a new application of permanent colour perfectly, or could be toned down with a temporary tint if you want to give your hair breathing space between chemical assaults.
*If you're planning to go from a dyed brunette to blonde please try this or similar products; high lift blonde home colours will not do the job and will wreck your hair. Whereas home colour removers are excellent and a hair salon will charge a lot to achieve the same result. But it can't return your hair to it's original colour and it'll need another colour applied to give a natural result, so maybe remove at home and book a salon colour to achieve the desired effect.:emo:
