Shadow the Hedgehog

Shadow the Hedgehog (シャドウ・ザ・ヘッジホッグ Shadō za Hejjihoggu?) is a fictional character from the Sonic the Hedgehogseries. He is an anthropomorphic hedgehog/Black Arm hybrid and the arch-rival of Sonic the Hedgehog. Shadow was created as the "Ultimate Life Form" (究極生命体 Kyūkyoku Seimeitai?) by Gerald Robotnik, using the DNA of Black Doom, and is the end result of Project Shadow. His purpose was to provide ways to develop a cure for incurable deadly illnesses, more specifically for Gerald's granddaughter Maria Robotnik, but he was captured and put into stasis by the military when he was deemed as a threat to humanity.

To be blunt, Shadow is a brooding and cold artificial being who enjoys being aloof and distant from everyone. He does not care how cold or blunt his opinion is, he throws it in anyway, making him come off as either rude or mean. He usually gives people the cold shoulder, even Rouge or Omega. Though he doesn't do that to them always. How careless Shadow seems can be changed. He is shown to be worried about Sonic and Tails' safety in Sonic Colors DS. Though he quickly dismisses this, Shadow is shown to not completely be heartless. Shadow can also sometimes be arrogant, thinking nobody can match or beat him. He also enjoys working alone, though helping Sonic save the world multiple times.

Appearances in the Retr0 Universe
Like Rouge, it is determined that when on a G.U.N mission, the Phantom Ruby appeared and started to shake and shudder, malfunctioning. A flash, Shadow and Rouge were both sent together to the Retr0 Universe at the same time. Though he, like Rouge, was not used to the land yet, he adapted to the strange land and continued being himself, the cold, aloof artificial.