Chapter One: Dick Grayson
It all started with Dick Grayson. Tim was taking his photos of Batman and Robin like most nights, sneaking along the patrol route to find the best angle of the action. This time, he chose a great spot behind a large potted plant on a roof and got some great shots of Batman and Robin taking down the Penguin's goons.
It wasn't until Tim was developing his nightlife photos that he noticed that Robin was going through his molting period again. Unlike Batman, Robin had actual feathered wings to aid his flights across Gotham City. Obviously, the Batman had bat wings. Sadly, Tim still hadn't figured out how Bruce Wayne and Dick Grayson hid their abnormally large wings during their daily lives. Secret of the trade, he assumed.
Anyway, Robin's wings were starting to fall out more easily, which wasn't unusual from time to time as he grew. This time however, the feathers growing in were not the typical Boy Wonder's green, red, and yellow. The new feathers were black and a few were an unusual blue. Tim thought the mix of blue, black, green, red, and yellow wasn't a good change, but Robin's feathers were probably not growing in those colors by choice.
It was shortly after he developed the picture of Robin's new molting when he discovered that Batman and Robin were arguing more. There were less inane jokes and more snarky comebacks. Robin was fighting a bit more fiercely and not taking orders well. Batman was getting frustrated with Robin, too.
Then, Robin disappeared. Batman was flying solo like he had during his first years in Gotham. When Tim read some newspapers, he discovered Dick Grayson had moved to Bludhaven. And, there was a new vigiliante there, too. Nightwing.
When Dick Grayson came back to visit once or twice, Nightwing had flown in Robin's place and his feathers had become completely black and blue. The red, green, and yellow of Robin were gone.