KOLOSSOS.

Kolossos is a towering, heavily mutated biological hedgehog created by Dr. Ivo Robotnik as an attempt at a living Metal Sonic. Due to the unstable mutation, he suffers from constant physical pain and mental instability, which has only worsened over time.

He was relentlessly harassed and bullied for looking too much like Sonic the Hedgehog, being called both a monster and an impersonator. Sonic initially comforted him during his early suffering, but as Kolossos grew into adulthood and his mutations became grotesque, Sonic grew fearful and abandoned him. This betrayal left Kolossos deeply distraught, filled with rage, and completely alone.

In adulthood, his mutation has progressed severely: his right arm has transformed into a large, fleshy spike covered in protruding bones, his mouth is completely hollow, and his eyes have hollow black sclera with glowing red irises. He stands significantly taller than Dr. Robotnik and struggles to control his violent impulses.

Kolossos is primarily silent and communicates through deep, demonic growls, guttural roars, and occasional distorted speech. He is sadistic toward his victims, driven by overwhelming hunger and rage. He survives by hunting and killing innocent Mobians, then eating their corpses to satiate his constant pain and hunger.

Despite his brutality, deep inside remains the lingering pain of abandonment and the memory of Sonic's initial kindness, which can occasionally surface as conflicted, unstable behavior when confronted by those who resemble his past or offer unexpected understanding.