Disclaimer: I do not own Sonic the Hedgehog, or any of its associated characters and lore.
Sonic the Eggman Imperialist
Green Hill Zone, South Island, Acorn Archipelago, Earth, 3230 Post-Xenos Event
For five long years, Sonic the Hedgehog, a blue-furred Mobian born with super speed, had lived alone on South Island with no knowledge of his family's whereabouts. In fact, his memories of them had been rather addled up. Depending on the occasion, Sonic "remembered" his parents either as a military airplane pilot married to a typical housewife with a baby girl Sonic figured was his sister, a literal robot married to a Queen with Sonic's usual raising being done by an "Uncle Chuck" who may have been a scientist, or some variation of the above. Although some of the other inhabitants of the moving South Island weren't unkind to Sonic, he nonetheless, lived a lone lifestyle that by the time he was ten years old, Sonic was confused of what his memories meant, bored of living on an island he had already explored completely by then, and, above all else, scared of how lonely he really was.
However, all of that changed one day when he came across a visiting Human who came to South Island in a fancy hovercraft and was immediately amazed when Sonic approached him at a fast rate.
"My word!" The overweight visitor exclaimed at the sight of Sonic's speed. Showing an eager smile at the curious blue hedgehog's swiftness, the Human said to him. "You may yet be the fasting living creature on this planet, my young friend! May I ask your name?"
Not seeing any apparent malice out of the Human who held out his hand in greeting, Sonic showed a slight smile and introduced himself as he shook it. "I'm Sonic the Hedgehog. What brings you to South Island, Mister?"
The newcomer chortled in amusement as if Sonic told a funny joke before amending. "Oh, it's "Doctor" actually, my boy!" After a moment of what looked like an internal debate, he added. "Doctor Ivo Robotnik!"
"Dr. Robotnik?" Sonic commented on how familiar it sounded, but ultimately pushed the thought aside and said earnestly. "Sounds like a cool name!"
The two shared a laugh before Robotnik went back to Sonic's earlier question. "As for what brings me here, Sonic, I'm looking for a set of valuable gemstones on this island that I wish to, let us say, personally study."
"Oh, you mean those Chaos Emeralds that are in the local legends?" Seeing Robotnik nod, Sonic replied honestly. "From what I understand, they are in a kind of extra-dimensional space that's connected to this island, but no one's been able to find them. I think I accessed it somehow when every time I ran fast enough to do so, but I don't know where to find the Emeralds or how to get them out."
Showing a clever smirk, Robotnik then said. "Well, how about we work together, Sonic? With your speed and my brains, we might be able to reach this Special Stage where the Emeralds are at and bring them together under our protection. I promise to make it worth your while if you participate."
Not seeing any wrongdoing on Robotnik's part and looking back on his own issues, Sonic complied. "Okay, Doc, throw in some chili dogs and give me a hand in seeing the world among other things, and you've got yourself a deal."
Robotnik once again shook Sonic's hand as they agreed, but before they got to work, he added. "I know this will probably sound silly to you, Sonic, but please call me Doctor Eggman as we work on this, all right?"
Sonic's penthouse apartment, Metropolis, West Side Island, October 24th, Five Years Later
In the years that followed since Sonic's first meeting with Doctor Eggman, he had risen in the ranks of the latter's Eggman Empire to reach the title of Egg Boss of the entire Acorn Archipelago. While he didn't cover a wide amount of territory compared to the Egg Bosses that enforced Eggman's influence in the nearby continent of Northamer, or even the surrounding ocean, Sonic was nonetheless recognized as the leading protector of the Empire's capital city of Metropolis as well as the Doctor's regent in the event the latter was absent or incapacitated. Although it was customary for every flesh and blood soldier of the Eggman Army to undergo Cyberization, Eggman initially felt that Sonic's achievements in helping him enlighten the entire Earth had earned him the right to not go through the procedure and with his superior speed, it wasn't like he needed any enhancements anyway, but Sonic ultimately volunteered to have his eyes replaced with green colored cybernetics if for no other reason than to show his soldiers that they were equals in the end.
Political and cyborg status aside, under Eggman's guidance, Sonic had seen the greater world, fought against many challengers which kept him from getting bored again, and found both a sense of purpose and comradery in the Empire, but despite his accomplishments, he had occasionally felt that he lost something of great importance as well. After helping Eggman gather all seven Chaos Emeralds to power the Death Egg space station and conquer the entire planet, Sonic underwent an exam that indicated that earlier in his life, his mind was fragmented by a teleportation incident and only through Eggman's advanced science, was it finally cleared up, but he lost many of his own memories from before he met Doctor Eggman. Nonetheless, Sonic decided to move forward and focus on what lay in front of him rather than behind. As the Boss of Bosses first lieutenant, he had no room for doubts.
"Hey, Earth to Sonic!" An energetic young voice called out next to him bring the Hedgehog back to reality in his own home. "Don't look now, Blue Blur, but I'm kicking your virtual butt!"
"We'll see about that, Cass!" Sonic replied positively to the girl on his right.
Since the date at the time was the tenth year anniversary of Eggman's first rise to power, many prominent officials of the Empire had arrived in Metropolis to take part in a citywide celebration and mingling that had earlier in the day began with a parade introduction of the dozen most prominent Egg Bosses and would soon continue with a huge gala to be taken place at the Doctor's personal citadel in the heart of the capital. Among the multiple visitors, was the green-furred sister duo that managed the Northamer Eggman Army, Egg Boss Clove the Pronghorn, who was four years older than Sonic, and her younger by six years Egg Underboss, Cassia, who Sonic was playing Chao-Calibur VI against while Clove was reading army reports forwarded to her on Sonic's left.
Although the two pronghorns enlisted more out of necessity and didn't share the same loyalty to Eggman as Sonic did, the latter was quick to befriend them since he and Cassia shared similar enough personality traits while Clove carried the mature aura he found attractive in a female just as she came to appreciate his earnest attempts to open up to them. It was through his relationships with the two, that Sonic did not feel much conflict about his current place in the world, and it was ultimately all the better for him as far as he cared.
However, with the gala about to start in the next hour, Sonic and Cassia had promised Clove that they would start to prepare for the big party once either of them died in the game. With each player doing their best with their controllers, it only a matter of them before either one's fighting character vanquished the other as Sonic himself proved with a sword slash on his Chao Knight on Cassia's Chao Thief.
"Yes!" Sonic cheered while Cassia groaned in defeat with Clove only shaking her head at the two with a nostalgic smile.
"Oh, just wait until later, Sonic!" Cassia declared with a vengeance, already planning to take the highest score in Chao-Calibur VI just as she scored Triple S in Devil Chao May Cry.
Clove quickly interjected with her hands raised. "Okay, kids, a promise is a promise. Now go freshen up."
"Aye-aye, Corporal Punishment." Sonic and Cassia sarcastically saluted much to Clove's amusement.
After a quarter of an hour, all three were in their Imperial uniforms. Sonic's a mix of black, red, white, and yellow in a similar fashion as the Doctor's while the two sisters wore gray dresses. A common occurrence for Clove, but not for Cassia unless ordered to.
"Shall I lead the way, my ladies?" Sonic offered with his hands out in a gentlemanly way.
Cassia and even Clove could not resist snorting with the former stating with sarcasm. "Yeah, right, and give those idiots in the media even juicier gossip along the way? No problem."
Clove's response was more diplomatic. "Thank you, Sonic, but I'm with Cass on this. I'd rather not be caught up in that kind of circus."
Scratching the back of his head sheepishly, Sonic replied. "Well, I am the fastest thing alive, and you can't blame a guy for trying either way."
"If you say so." Cassia commented before leading the way out of the apartment herself and straight to the hover car Clove loaned for the visit to take the three of them to Citadel Eggman. As each Mobian strapped their seatbelts in a similar position to when they were lounging earlier, though, Cassia took the initiative to leave a kiss on Sonic's right cheek and pulled Clove to do the same on his left against her will.
By the time Cassia felt she was done and let go of a blushing Clove, Sonic was a blushing mess himself and barely paid much attention to Clove's embarrassed outburst while Cassia merely giggled too innocently for either her sister, or their mutual friend's tastes before the exasperated Clove finally gave up and started to drive away.
While I was internet searching, I learned of another Sonic AU in the works by one Kimmy-k0 that operates under the tagline "if Eggman was Sonic's father" which also affects Tails and Amy Rose at least among other characters as well. However, I while I can imagine some ideas to make a genuine Eggman Imperial ally out of Sonic to the point of potentially becoming an Egg Boss as Dog22322 on DeviantArt depicted just as others on there made fanart of him with cybernetic implants, I think I would need more room to work with before I eventually write about such a concept in full myself.
Nonetheless, considering I wanted to get one last paid post on my Pat-reon before June ended, and I was having trouble brainstorming on other works to make the cut before I had a quick thought about the Egg Boss Sonic fan art mixed with some other verses, I felt that I had a good enough idea for a one-shot fanfiction if I just acted on it. The references to Sonic's family include the first Archie continuity, an old Sonic manga that apparently introduced Amy Rose and Charmy Bee to the world before the games ever did, and Sonic Underground (but without Sonia and Manic because while I have nothing against them, I think Amy and Sonic's evil counterpart, Scourge, are the only pink and green Hedgehogs of major importance we need respectively) while I made a reference to the Soulcalibur series of video games in a Chao-centric kind of way to go with the setting and tradition among other things, but while I can imagine Sonic paired with either sister whether he's on the Empire's side, or helps them defect, I kept it ambiguous as best I could since I couldn't decide which girl to go with him in this, and even though I enjoy a good, workable harem, I do not think Sonic is that type of franchise.
Hope you found it alright enough, all the same.