(there is so much blood in this broken world.)
Blood is the most vibrant shade of crimson when it first flows out of a wound, big or small. Then it darkens to a more serious, solemn shade of red. Blood still has a metallic tang to it for Kaneki, but he doesn't really mind- Blood is one of the necessary components of a human, and therefore, it is necessary for him to survive.
He used to be repulsed to some degree by the sight of blood. Now, when he is hungry, it beckons with a stained finger and pulls him ever closer. When he is hungry, blood tastes like heaven...no, humans taste like heaven when he is hungry, and he knows he can never get nutrition from anything else. It is a sad existence.
Thankfully, he knows that he does not have long to live at all, since Aogiri Tree, the CCG, and everything else seems to have a desire to see him dead. Haise Sasaki, his jailor and the current owner of his- no, their body just wanted him to go away. Or give him power, depending on the state Haise was in. It was infuriating, sometimes. The once great Centipede, taken down by Arima and given a new identity as an Inspector, of all things. Why hadn't Arima just killed him?
Haise was a threat. That Kaneki knew, and Arima knew. Haise would be even more dangerous if the careful barriers in his mind weakened even further, letting even more of the essence of Kaneki take over. And Arima couldn't kill him without the Quinx hunting him down, probably, for revenge. That was just how teenagers were.
Sometimes he just wants to scream. To scream out loud his hatred, his frustration, his anger. He has done that, actually, but negative emotions keep piling up. Which, to him, is not surprising at all. He carries a burden on his back, the burden of all his precious loved ones' lives. And they do die...well, that's just what being a ghoul is- fighting for your life, killing, eating, loving, betrayal, and, most likely, a gruesome and painful death.
And then, the torture. He knows most ghouls haven't and never will go through this, but the unlucky few that have (including him) are damaged beyond repair.
This is why, at the Tsukiyama headquarters, Ken Kaneki knew, approximately, what the Rosewald ghoul had gone through with the One Eyed Owl. It had scared him, how Rosewald had turned out like that. What would he have become, if the others had never saved him?
Even as he was trapped inside Sasaki, he could feel that something had changed in the former Quinx. But he would wait. And keep waiting, until he could overpower Sasaki and take his vengeance on the world and himself.