Who is Rover?

Grover?

Grover Underwood is the character, who often pretends to be human. He is actually a Satyr. Grover met Percy at Yancy Academy, where they quickly became best friends. Grover described as scrawny and crippled. He is crippled because he is a Satyr, half man and half goat, though his true form is hidden by the 'mist'. To the outside world, Griver looks like a crippled boy, but in reality he is a satyr.