tgre-news:

1) Hide overheard Kaneki’s conversation with Yoshimura. From here we can deduce that Hide knew Anteiku is helping Kaneki to live as a ghoul. That’s why he revealed Kaneki’s secret habit of touching his chin when lying to Touka. He probably already knew Touka is a ghoul and that she has a close contact with Kaneki.

2) Hide is said to have been collecting news clippings, reading books about ghouls, watching news coverage related to ghouls - basically he has been researching about ghouls just because he wanted to help Kaneki.

3) Hide saw Yamori and Nico entering Anteiku, which prompted him to place a tracking device on Yamori’s shoe. This led him to discover Aogiri Tree’s hideout in 11th Ward. Then, he leaked the information to CCG in hope that they could save the captured Kaneki.

4) Hide joined CCG after the incident in order to look for Kaneki. He isn’t like CCG investigators who are trained to be one, yet he is willing to risk his life to find his missing childhood friend.

5) This is just my speculation but I believe Kaneki being taken in by CCG was Hide’s plan all along. He knew that that was Kaneki’s only chance of survival. Without Hide’s interference, TG might have really ended in a tragedy, and we got no TG:re and Sasarious.

In short, Hide has been doing everything behind the scenes with the sole purpose of saving Kaneki, the opposite of Clowns who were doing everything they could to screw with Kaneki’s life.