Brindle
   Brindle is a pattern, not a color. A brindle coat exhibits a tiger-striped pattern resulting from layered black hair intermingled in areas of lighter color: ie: lighter color with black stripes.  Reverse brindle occurs when the black striping is so heavily concentrated that the lighter background, while clearly still present, is much more subdued, giving the appearance of the coat being black in color with lighter stripes. Brindle Can come in most colors. 
   The brindle color will ALWAYS be present in the coat no matter how often or how short the coat is taken down.  This is the same pattern that you can see in Great Danes, Boxers, and several other breeds.  Brindles even if shaved clear to the very skin, will still display their stripes.  The brindle pattern is more noticeable if the coat is kept short on the poodle.  If the coat is grown out it all mixes together and gives the dog a more solid looking color all over, albeit a muddy looking color.
​Since most poodle colors fade it is very common the striping on a  brindle to become less distinct even nearly invisible over time.
​Brindle is a recessive gene and both parents must carry it.

Tiger Lily at 9 months

Tiger Lily at 5 years, showing the fading progression