I was thinking of adding some manic panic or SFX black to my conditioner to deepen up the color every once in a while, but I was worried if i cut it with conditioner it would just turn the color it faded to? If its brown that would work fine still, but if they fade to blue, that would be a no-go. Anyone know if my theorizing is correct? and which would work better for me? Or if any other veggie dye would (I'm in the US btw).

thanks in advance! i figure if anyone might know this random question, you folks might :)