Mido

Mido is the moody leader of the Kokiri in Ocarina of Time. He has a reputation of being mean to others and bossing them around, but he respects the Great Deku Tree and craves to be liked by Saria. This might be either source or fuel for his condescending attitude towards Link, who is both favoured by the Great Deku Tree and best friend to Saria. Mido's prime target is Link's "not quite Kokiri-ness", such as that for a long time Link didn't have a fairy partner, resulting in Mido calling him "Mr. No Fairy".

Despite this, Mido is not a bad person. His jealousy of Link does not stop him from giving advice to him and in the future years, he's genuinely sorry for the way he treated Link. He can be depended on, even in the face of danger, and at least holds the trust and loyalty of Fado.

Ocarina of Time
Mido guarded the road to the Great Deku Tree and refused to let Link pass if he didn't have a sword and a shield. Additionally, he was not at all thrilled the Great Deku Tree had summoned Link instead of him, something he made sure to have Link know. When Link returned with the required equipment, Mido was greatly displeased and reiterated that he would never accept Link as an equal.

Unfortunately, Link's visit to the Great Deku Tree ended with the latter's death as a result of the curse laid on him by Ganondorf. When Mido found out the father of the Kokiri had passed away, he immediately lay the blame on Link, further motivating him to leave the Kokiri Forest.

In the seven years that Link was gone, life in the Kokiri Forest became tough as Ganondorf's evil spread from the Forest Temple and caused the Kokiri's home to be infested with monsters. Mido went with Saria to put a stop to it and on her request guarded the route to the Sacred Forest Meadow, so that no one could follow her. When Link met him in the Lost Woods, Mido did not recognize him, although he noticed there was something familiar about him. As such, he did not let him through either until the stranger played him Saria's Song and thereby proved he was friends with Sari. When Link came back after helping Saria awaken as the Sage of Forest to tell Mido that she would not come back, Mido became upset and asked the stranger that, if he'd ever meet Link, he would tell him that Saria had been waiting for him and that he was sorry for having been mean to him.

Mido was last seen at the liberation celebration at Lon Lon Ranch. He was sitting next to King Zora, both seemingly worrying about what had happened to their loved ones.

Theories
Fado is Mido's sister - It is speculated that Fado is Mido's sister. Aside from having similar names, Fado often displays concern for Mido's opinion. When he blames Link for the death of the Great Deku Tree, Fado is the only other to repeat that accusation to Link. When talked to with a mask on that Fado doesn't like, she threatens Link she will tell Mido about it and that he will beat him up. In contrast, when she's spoken to with a mask she likes (except for the Skull Mask ), she requests Link that he doesn't tell Mido. While it is possible Fado's simply a very good friend of his, the dialogue supports siblinghood just a bit better.

Trivia

 * In The Adventure of Link, there is also a town called Mido.