Conan Edogawa and Ai Haibara
Sometimes everyone think both Conan and Haibara have a special relation and friendship that nobody would understand. This is particularly true for members of the Detective Boys who often try to question their relationship.
In some episodes and manga chapters, Haibara would give hint to Conan about her feelings towards him. But in the end, she would always told him that it's a lie. Even though everybody including The Detective Boys, Sonoko, Ran and the other know about Haibara's secret feelings toward Conan, he never realizes it.
It's also been shown that Conan has a strong feeling to protect Haibara if anything happens to her. For example on the episode where Haibara stayed in a bus that has a bomb in it, Conan immediately saved her and tell her to accept fate and never turn back.
