Here are some character summaries. (If a character is missing, I probably haven't gotten around to writing theirs yet.) For each character, their name, species, age, alignment, and status (as of the end of the main fic) will be listed, as well as a short paragraph about the character in question.
Alignments are given as good/neutral/evil, with an alliance added in parentheses. Alliances are typically organizations that have members, like the Resistance or the Empire.
Name: Zero
Species: Jackal
Age: 18
Alignment: Good (Restoration) (formerly Evil (Empire))
Status: Serving community service (with credit to time served)
Zero, formerly the Ultimate Mercenary, lost his Jackal Squad in an incident while defending an Eggman base in the Mystic Jungle. Following that incident, he had the Phantom Ruby implanted in his chest. No more was he Zero; he was now Infinite . Following the events that happened before the fic, he was revived, but he has a large scar on his chest where the Phantom Ruby once was.
Name: Gadget
Species: Wolf
Age: 18
Alignment: Good (Restoration)
Status: Free
Gadget, the brave hero who joined Sonic and took down the evil Empire, happened to have a run-in with Infinite during the war. Following the war, he felt downtrodden, thinking he'd never see Infinite again. You can imagine his surprise when he found Infinite, barely living, in an alley. Now they live together and have their happily ever after (at least, for the time being).
Name: Dr. Ivo "Eggman" Robotnik
Species: Human
Age: ??? (late 50s - early 60s)
Alignment: Evil (unaligned) (formerly Evil (Empire))
Status: Serving life sentence without parole
Dr. Ivo Robotnik, a mad scientist with a very high IQ, built an Empire in little more than six months. Utilizing a before-unseen gem, the Phantom Ruby, Eggman was able to create the ultimate soldier, who he named Infinite. With Infinite at his side, there was nobody who could stop him... or so Eggman thought. After Sonic's escape from the Death Egg in September 22XX, Eggman was quickly and summarily defeated. He managed to get away and regroup, but he suffered his final defeat at the hands of the very jackal who had once been Infinite. He was convicted on over 25 counts of war crimes, as well as just general jerkness, and is currently serving his life sentence without parole.
Name: Dr. Alexander Starline
Species: Platypus
Age: ??? (definitely younger than Eggman lol)
Alignment: Evil (unaligned) (formerly Evil (Empire))
Status: Free (following 6 month sentence)
Dr. Alexander Starline was fascinated with Dr. Eggman, ever since the latter began his world conquest. After Eggman's first defeat at the hands of the Resistance, Dr. Starline tracked him down and helped him regroup, even stalling out the Resistance in a battle within the city. However, he was captured alongside his idol, and was sentenced to only 6 months (having not committed any crimes deserving of a longer sentence). Now free, he has pledged himself to take up evil in Eggman's stead.
Name: Restoration
Alternative Names: Resistance (former name)
Leader: Knuckles
Formed: March 22XX
Dissolved: N/A (reorganized in September/October 22XX)
The Resistance was formed after Sonic's defeat at the hands of Infinite to defend against the Empire's aggressive expansion across the planet. They defeated the Empire for the first time in September 22XX, after retrieving Sonic from the Death Egg. Later that month, they defeated the Empire for the second and final time, arresting its leader, Eggman, and causing its dissolution. Following the final defeat of Eggman, the Resistance reorganized, becoming the Restoration and aiming to restore the world as close to its former state as possible.
Name: Empire
Alternative Names: Eggman Empire
Formed: March 22XX
Dissolved: September 22XX
The Eggman Empire, in its prime, controlled around 99% of the world. Led by Eggman and his right-hand man Infinite, the Empire had a simple ultimatum: "Submit or die." It was considered to be dissolved in September 22XX, after Eggman's final defeat and arrest at the hands of the Resistance.