Born in darkness, Atarangi began life in the shadowcaverns - a vast network of tunnels and chambers running through the body of the Great Spirit Robot - as one of the mysterious Ak-Matoran. It is here that he was exposed to raw elemental energy flowing from a rupture in one of Mata-Nui's internal systems. Rather than destroying him, the energy awakened Atarangi's body and transformed him into a Toa.
...I don't have too much time to write this sort of stuff up anymore, but basically he goes and serves Mata-Nui and lives on the Island of Korrothis and does freaky mind stuff, and when the Great Catacylsm hits and the Red Star malfunctions he fuses with 2 of his team-mates and gives up his individuality in order to serve as a sort of grim reaper for the Matoran Universe, allowing its residents to die. Hooray~
And yes, he is based off Toa Shadow. Atarangi is the Maori word for "Shadow", and this guy's actually been a WIP for me since before Minion was a thing. I'm that slow at MOCing because University and all. :V
The lower arm design belongs to Oblivious. The character belongs to ClockworkTempest. Everything else is from me.