When Ghoul #240's eyes had healed, he saw the world in black and white. To begin with, it didn't bother him, for how could it? He was living in a small call with no one but Arima-san for company and pictureless books for entertainment.
But then he got a name.
But then he became Sasaki Haise.
But then he began to interact with the world around him.
At first, he tried to not let it bother him. As it was, he was lucky that Arima-san was letting him live in the first place, let alone working for the CCG. What did it matter that he couldn't see what colour the grass was or seeing what shade the sky was a certain part of the day. He was lucky enough to see the world in its black and white state. So he didn't let it bother him.
But as time went along in its course, he began to wonder.
What colour was the grass?
Does the sky really change colour throughout the day?
What colour does the blood flow out of the ghoul after he cut the head off?
What colour did his eye go when he ate his meal?
Arika-san could see the colours, for she continuously moaned at him when he filled out the paperwork with red pen (is that the colour of rivers?). When asked about her soulmate, she muttered something about him being missing and quickly changed the subject.
Arima-san too could see colours, for he hated with when he got blood on his clothes from the latest whack-a-mole mission from the 24th ward (was blood the same colour as the leaves as they fell of the trees in autumn?). He had told Haise that his soulmate was a female writer that had lots of fans. When Haise asked why they weren't in a relationship, Arima had told Haise that just because they were soulmates, it doesn't mean that they had to fall in live and be together for the rest of their lives. It was better for them to live their own separate lives rather than try to merge them together.
(Haise didn't really get it, but he left the subject alone.)
After these conversations, the fact that Haise couldn't see the colours began to bother him, to the point that he began to get angry with himself that he couldn't watch the sky turn different colours or know what colour was fire and how that was different to pouring coffee into a cup.
After these conversations, he began to have nightmares.
They were in colour.
It confused Haise to start of with, but as more nights lasted with him say in a chair, watching an angry looking liquid run from his missing fingers and listen to the screams of the person behind him did he meet a small white haired child.
His name was Ken.
Ken had known all about colours since a child at school had joined his class, but didn't tell Haise what happened.
He knew what grass looked like and he has the knowledge of how the sky changed through the day but he didn't describe the differences to Haise.
He knew what happened with their relationship, but he didn't clue Haise in on the end result.
He didn't tell Haise what happened to their soulmate, but Haise wasn't sure if he wanted to know.
He'll never know what colour the grass, the sky, the blood dribbling down his lips and the meat that sated his hunger was. But that was okay, in a way.
You can't miss something you've need had.