Humanity, a species much like our own, able to have many shapes and forms. In my experience with the humans I have learned much, their capacity for compassion and love, as well as their greed and violence. But like all things, there is much more to the single human, then meets the eye. I am Optimus Prime, and this, is the story of Luna.

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Jasper, NV. Midnight.

Luna walks up to her house late at night, hoping to not find her parents waiting for her when she gets indoors. She takes a deep breath and goes to put her bicycle in the garage. She starts to hear a strange noise from outside, like men talking but not so loudly. Luna gets curious and walks out to find a huge shadowy figure looming over her house and points a bright light at it; suddenly her house is aflame.
Luna screams and runsfrom the open door and into the road. She hears something follow her and doesn't dare to look back. She knows it would only make her run slower, and she doesn't want to glance at her house, knowing her family is asleep there. Luna starts to go through her options she made up in her head, then; she spots a random semi truck in the end of the cul-de-sac. She doesn't have enough stamina to keep herself running and she canhear someone gaining on her. She quickly picks at the lock and opens the door, shutting out the figure.
"I-I need to find somewhere better to hide… hope this person didn't need their truck for a while." Luna whispers to herself as she breaks open the bottom of the steering compartment and starts to hotwire the truck.
A minute passes, and it appears like the engine is ignited when a huge, bright blue spark jumps at Luna. She yelps in pain, pulling away her left arm faster than her right. The spark of energy grows brighter and starts to eat away at her skin and muscles of her right arm. Luna feels a jolt as the truck starts to move and steer on its own. She tries to breathe and stay calm, but under the pain she is going through, she holds her hand over her mouth to keep herself from crying or screaming.
A while later, Luna feels slightly dizzy due to her ongoing blood-loss. Her arm had "dissolved" to under her elbow, and it continues to slowly go away. The truck soon stops inside what looks like a secret hideout built at a huge scale.
"I need you to get out now." She hears a deep voice come from inside the truck.
Luna doesn't want to question anything at the moment, doing as she was told. She looks at the truck in awe, for as soon as she got out, the vehicle had started to move and transform into a massive robot. Luna stands speechless for a few seconds before making a loud scream.
'This can't be happening! There's a huge ass robot right there and it was from the truck! HOLEY SHI—' she stops mid-thought in a near faint.
Her blood seems to still seep through her fingers as she tries to cover what is left of her arm. The huge robot kneels down, picking her up gently, taking her to another room. The robotic organism puts Luna down on a large, inhumanly sized examination table.
"Ratchet, have a look." It speaks.
"Prime, when will you stop bringing MORE humans into our base? We aren't running a daycare here." Ratchet walks over to the table Luna was lying on. He narrows his optics and zoom on to her arm. "Hmmm, interesting."
"What is your diagnosis?" Optimus Prime asks, looking a bit nervous.
"Well, aside from the typical human problems, her entire right arm has dissolved after making contact with the energon that flows through you, it's burned right through the bone, and she seems to be losing blood at a rapid rate and will soon go...'offline.'"
"Ratchet, her injury is a result of my own actions, if there is any way to help her, please do so." Optimus looks slightly scared, but soon shakes his head and with a mechanical poker-face.
"Well...as far as I can tell, there's no way to seal the wound, nor is there a way to replace the arm; the energon remaining there will surely burn any material it touches."
"What about Cybertronian metal? Surely it cou—"
"Prime, you know as well as I do, internal Energon is specified to a single unit, the Energon buried in her would only be compatible with your body. This is why it reacts so violently with other foreign bodies." Ratchet shakes his head, watching the Energon slowly eat away at the rest of Luna's arm.
"Ratchet, there is only one option then." Optimus walks over to a parallel table and sits down. "You must fashion a makeshift arm for her using portions of my armor." Prime points at a section of his armor while talking.
"Optimus, surely you cannot be serious," Ratchet groans, rubbing his forehead. "Why would you cause yourself damage just to save ONE human. You said yourself she was only inside of your vehicle mode so she could try to steal you."
"One's right to live can't be judged based on their actions. Freedom is the right of all sentient beings, Ratchet, and she deserves the freedom to live. Perform the surgery, old friend. That is an order." Optimus sits more upright,  getting ready.
Ratchet lets out a sigh.  "There are days I wonder if that compassion of yours is A strength or a weakness, Optimus…" Ratchet pulls out a laser saw, "I'll see you after this is over, sir."
Hours later, Ratchet completes the delicate act of building a new arm for Luna out of the section of armor Prime chose. It was successful. Luna starts to shift and wake from the anesthesia. She groans and rubsher eye. A sharp pain goes through her head and arm.
"Ugh… My... Everything hurts," she whines, blinking as she tries,to lift herself up, falling back down onto the table. "What the--!?" Her eyes widen as she starts to look around. "Where the hell am I?" She tries to sit up again and falls once more. "Why the-" Luna gasps when she catches sight of her right arm. She stares at the robotic arm that now occupies half of it. "That's….creepy." She uses her other arm to sit herself up, taking another look at her new arm.
She strokes the metal-and-fire design, stopping at the mysterious symbol. "What the heck is that made up of?" She examines her hand closer and is very intrigued by it. She tries to remember what happened recently, only to have blurred thoughts. Then she remembers a truck in the end of her path when she was running away last night.