@sparkxii @whitephobic-cyclonus Okay, woof, here’s the background of the AU if you’re ready.
In the early 1960’s during Spike’s childhood, the Autobots develop an outpost on Earth and are discovered by the WWII military veteran and mechanic, Daniel “sparkplug” Witwicky, Spike’s dad. The Witwicky family keeps them a secret and Spike’s childhood is filled with the wonder of these amazing aliens that share their mechanical anatomy with a marveling Daniel, who teaches it to Spike. They give him and his father Cybertronian names and the interactions cultivate Optimus’ love for human organics specifically.
Spike’s best bot friend growing up is still Bumblebee, but the amount of Autobots on Earth at this time are small, and they come and go. Optimus, Bee, Hound (and his military unit), and a young Ratchet (and his medical unit). Spike and Daniel were kept in the dark about much of the Great Cybertronian war, with Optimus just making vague comments about their reason on Earth being that they were looking for places to start again, places to keep safe from their races own mistakes. The Cybertronians eventually stop visiting during the late 70’s, but the Witwickys never stop waiting for them subconsciously.
In the late 1980’s, as Spike graduated, he accepted a non-combatant US military contract in order to get a free college fund. He served as a mechanic for military ground vehicles on standby for the ‘Cold War.’ During this time, Skywatch digs up the bodies of the Decepticons buried underneath Mt. St. Helens from Shockwave’s canon fuckery that took place in pre-history.
Several attempts to identify the techno-alien life are made by Skywatch to no avail. They eventually end up completely dissecting Bugly, one of the excavated bots they had to offline after he reactivated and tried to escape.
They distribute the pieces to various talented military personnel in a top secret project to try and figure out absolutely anything about the tech. Spike, who’d become the most renowned mechanic in his unit, is selected and given a piece of a transformation cog. He instantly recognizes it and panics, but pretends to not understand the device. Still, he tries to take a tiny piece of it home with him to show his dad. Skywatch pays close attention to Spike’s reaction, and lets Spike get away with stealing the piece in order to track him.
They catch Spike presenting the tech to his father and arrest the two of them, taking them to Skywatch. In order to not let his son be imprisoned for treason, Daniel agrees to become the official informant on Cybertronian life for Skywatch. Spike is moved from his unit to the research facility as well and works on dissecting the other two bots with his father and the Skywatch team headed by Chip Chase.
But the tech is complicated and the research is slow.
Then, in the 90’s, the Decepticon attack of Earth happens the same way it did in All Hail Megatron for the same reasons.
The Seekers strike first and burn the entirety of Airforce One within seconds. Spike and Daniel are both there with Skywatch to watch it happen.
NYC is completely leveled, thousands of humans are instantly vaporized by Cybertronian weaponry, or crushed underfoot, or gleefully torn apart with claws and teeth by particularly sadistic bots spurred on by Megatron’s anti-organic propaganda he’d proliferated amongst his men. Prowl and his special unit including Jazz, Arcee, and various others, are deployed to Earth to try and mitigate the damage, but the fighting is still catastrophic. Still, the Autobots manage to temporarily push back the Decepticons.
Spike is drafted to a combatant position after this first attack and is pants-shittingly terrified after seeing what a blood bath the first assault was. The US military had offered literally zero resistance and all personnel who’d been deployed were dead now or severely injured. But this time they had the Autobots, specifically a couple bots he recognized. Optimus Prime, Hound (and his unit) and Ratchet. But Spike’s interactions with Prowl, the leader of the special forces unit that had first routed the Decepticon attacks, is what is the main focus on the AU.
The two become mirrors of each other: their stubbornness, fear fueled distrust, and obsessive behaviors pushing each other into deeper, unhealthier habits during the war. When the Decepticons are defeated and the Autobots remain on Earth but go into hiding, that’s when I believe the actual “romantic” side of things kick off. Spike is traumatized by war, and is confused by his simultaneous love and fear of Cybertronians.
The same time Skywatch begins to dabble in their treaties with the Decepticons, Prowl reveals more of his own shady activities with the Constructicons, and that doesn’t do much to quell that fear in Spike.
Eventually the unforgivable happens and Spike kills Scrapper by himself. He says it’s a way to prevent Devastator from forming again, but deep down it’s to prove to himself that he could take a Cybertronian life without fear. That’s the point of no return for him, and his relationship with Prowl spirals into vitriolic enemies from there.