(..You  know, Toichi probably is the reason Kaito’s so emotionally isolated and not social outside of Aoko. Not just with Kid and probably moving around a lot when he was younger, but… He kept Kaito with him more often. Didn’t let him stay with Aoko at that show, he picked him up and took him away to teach what poker face was. When Kaito did a trick and tried to be friendly towards Yukiko, Toichi picked him up and told him not to bother people. In the past, we can see Shinichi able to go off on his own and, is in fact, encouraged to. Kaito you only ever see with Toichi, outside of that one time with Aoko at the clocktower.

What if Kaito was encouraged not to talk to people? Be friendly, but not to trust? Toichi was clearly close, but… something went wrong, there… Have to wonder if he almost lost Kaito once from trusting someone and became overprotective, but Kaito doesn’t remember, what if it ties in with the fish phobia, what if someone tried to drown Kaito to where Toichi became so protective it was detrimental-:Edit: Actually, kidnapping is more likely, maybe the person kept him in a room with fish, to where he associated the experience with the things, especially since it also meat separation from his father and his phobia may have become worse after losing his dad…)