This is based on MissCHSparkle's Breaking Free/Stand By Me G1 AU, and a moving pic on deviantART [fav . me / 106384658] It'll make sense if you read Breaking Free, but can be read as a stand-alone. In case it's not clear, Starscream, Skywarp, and Thundercracker are Autobots here.
It couldn't be.
Skyfire couldn't comprehend it. It seemed unreal; the fact that his bondmate was offline permanently, brutally decapitated by Megatron.
They had been out on patrol when they were ambushed, and Skyfire had been temporarily paralysed by a blow to the head. Slumped against an embankment, he was forced to watch his bondmate's gruesome death.
"You really thought you could escape me by joining your enemies?" Megatron snarled, holding Starscream in a chokehold. The terrified Seeker could only squeak out a faint, "Yes!"
"Well, you were wrong," Megatron growled. "I don't tolerate my second-in-command defecting. I said you would pay, and now you will."
Skyfire was helpless to watch as Megatron started squeezing Starscream's neck harder, the Seeker's expression growing more pained and terrified. He managed to turn his head to look at Skyfire one last time, flashing a message with his optics.
"Goodbye, Skyfire. Take care of my trinemates."
As the message finished, a loud crack rang out as Megatron suddenly jerked on Starscream's neck, completely severing it. Cold horror spilled through Skyfire as the Seeker's body slumped to the ground, turning ashen while spewing energon from the severed neck.
The shuttle winced as sharp pain stabbed him as the sparkbond he shared with the Seeker was forcibly broken.
Megatron held the decapitated head in front of himself. Taking a long look at the now frozen expression of pain, he laughed manically.
"It serves those traitors right!"
He threw the severed head at Skyfire, and then flew off, laughter fading into the distance.
As Skyfire recovered from his paralysis, he glanced at the severed head. Almost as if he were in a trance, he grasped it and stared into its face. The often cheerful face was now frozen in a state of pain—the once vibrant red pools now devoid of life…
It was too much to comprehend.
Holding the head close, one optic leaked a single, pink tear for his mate. Deep in grief, the time seemed to pass by all too fast, and he barely noticed the arrival of Skywarp and Thundercracker.
They had felt the trine bond being severed while on their own patrol. Realizing something was grievously wrong, they immediately made for the area where Starscream and Skyfire had been patrolling, comming a warning to the base that something was wrong with Starscream. They had expected a serious spark injury, but instead were greeted by a sight too horrible to imagine.
The headless body of Starscream lay loosely on the ground. The upper parts of the body and the surrounding ground were covered in drying energon, making for a gruesome sight. But that was hardly anything compared to the next sight.
Skyfire was standing nearby, holding Starscream's decapitated head, his arms trembling and muttering incoherently.
"S-s-sk-skyfire," Thundercracker finally broke through the shock enough to whisper, "What happened?"
Starscream's head dropped to the ground with a heavy thunk. Skyfire slowly looked up at the Seekers, a grim but determined expression on his face. Feeling the fire burning in the shuttle's cyan optics, they froze.
Skyfire's normally soft voice was low and dangerous as he answered Thundercracker's question.
"Megatron will not get away with this. He WILL pay."