Grim is a former toa who now works for the Empire of Darkness.
Grim was once a matoran of sonics engineer named Korik from De- Koro. Once turned into a toa by Takanuva, he was unable to control his powers safely due to having to no prior training. Slowly, his brain became more and more damaged, until going practically insane. He was a killing machine, and was used by the Empire as a weapon of sorts. He slept in a protosteel vault, due to an... incident in his sleep involving a skrall soldier. Basically, that skrall won't have to worry about anything anymore.
Being a toa of Sonics, Grim is able to control all sound. Despite his range of powers, he usually chooses to use a sonic scream of sorts, knocking back, or even knocking out, deafening, or killing his victim. He also has a single sword from his early days, but never chooses to use it due to his current state. Or perhaps he just doesn't know how to use one anymore. No one would be surprised, really.
the Attack of the Empire Edit
When the Empire attacked New Atero, Grim was still in his vault. When he realized what was happening, he eagerly rushed to the city, hoping he didn't miss out on all the "fun". He kind of did. Fortunately for him, he saw Tarakal: A traveling skrall who belonged to neither side, and well... You get the drill. He eventually battled Arilam, a toa of Lightning, and Orokal, Arilam's friend, who was a toa of fire. Grim was overpowered, and knocked out. While the two had their backs turned, a strange cloaked being picked him up, and carried him away. His current location is now unknown.