Shadow the Hedgehog (SUT)

Shadow the Hedgehog is an artificial Mobian hedgehog who is one of Sonic's greatest rivals and often fights with guns and swords. His main goal is to destroy the evil Dr. Eggman once and for all as well as fulfil Maria Robotnik's last wish.

Past
His past is near identical to the one in the official Sonic canon that SEGA made which his him being made by Professor Gerald Robotnik to cure his Granddaughter

from a deadly disease called N.I.D.S. But the Government shut it down, and they did it violently. Shadow was led to an escape pod by a fatally wounded Maria, and was sent down to Mobius, where he was found by GUN and was locked away... Unfortunately, Shadow forgot most of these except for Maria's last moments. During his time in containment, some old Drakon tech allowed him to speak to Dr. Ovi Kintobor, but after Kintobor turned into Dr. Ivo Robotnik and took over the world, Shadow was placed in a more secure cell.

Things were the same for Shadow until his death, where he died, but Dr. Eggman built a robot to put his consciousness in, and after Sonic heroes, he was given an Organic Body by The Black arms, and his history then became the same as his game counterpart.

Eggman's return, and world merging
Shadow was part of Eggman's all out attack on the Freedom Fighters, and although he fought well, he was overwhelmed by Super Badniks, but luckily Sonic the Hedgehog put a stop to Eggman's attack.

Shadow also helped a bit in stopping Eggman from taking over the Multiverse by sneaking past defenses and getting data from Eggman's computers, with some help from Rouge the Bat and Omega.

When the world was merged, he had a tough time getting used to people like Darkwing Duck (Actually, mainly Darkwing Duck in General) always showing up out of nowhere, and interrogating him due to his Shady appearance.

Multiverse Merged
While he didn't have a big role in the fight to get the Multiverse apart, Shadow did help in taking down bases and baddies, and appreciated when Sonic and the others got saved the day.