One of the main things that Blackwing did was make everyone the same.
Same colours, same clothes, same people. Constantly. For years.
The first time Dirk escaped he was floored by the sheer amount of colour in the world. His world had been one of grey fabric and grey faces and grey rooms, and to see all these people wearing entire rainbows on their bodies was a concept Dirk had found himself falling instantly in love with. So naturally, as soon as he sees the jacket, he knows he has to have it.
It’s a bright, cheerful yellow, like the essence of sunshine in a piece of fabric. Dirk doesn’t have much money at this point, and almost bankrupts himself buying the thing, but the feeling he gets when he puts it on is worth it. It’s so perfectly, unabashedly colourful - so unlike anything Blackwing would have allowed him to wear. Shrugging it on, it feels like he’s finally beginning to step out of their shadow.