While she is involved in other Transformers universes, my OC Lily is popular in the Transformers: Prime universe. But her fate is all the same--going from human child to an Autobot child due to some horrible accident (which varies in the different universes).
If you are interested in reading her story, you can go to this link to know more about her. The story is currently incomplete, however, and is written by me:
In the TFP world, Lillian Abigail McElroy is a small little girl who lives in a home on the outskirts of Jasper, Nevada with her widowed father. Her mother had passed away under extreme circumstances.
Compared to the height of a 6-foot man, she only comes up to barely above his waist. Despite being seven years old, she can't quite reach the ground when sitting on a swing. She has fair skin, short, grizzly brown hair, and pale, green eyes. Her preferred outfit of choice are her pajamas, which are a large, baggy, green shirt, pink shorts, and she wears a pair of socks. Her favorite food is a cheeseburger and chocolate shakes with marshmallows; favorite drink is apple juice. Lily used to be outgoing and a chatterbox, but after her mother's tragedy, she is shy and keeps to herself. Because of her PTSD, constant nightmares, and unpredictable reactions to certain things, she has lived a sheltered life with her father, for her own sake and the sake of others.
She meets Team Prime before becoming an Autobot, and she instantly bonds with Optimus Prime. And learning that they have a similar background enhances their bond even more.
In the TFP universe, Lily's body is built by Alpha Trion, but many, many years before she was born. The body originally belonged to a youngling named Amira (who will have her own page soon). After Amira died, Optimus took her body to Earth and hid it in a vault of their missile silo base. After Lily becomes fatally wounded during a battle, using Autobot technology, her mind was transferred from her human body into the Autobot's.
The body is assorted of different shades of pink, her body is figured like a child; the plating around her waist resembles a skirt, and she has pigtails that move based on her emotions [happy--fluttery, sad--droopy, angry--rattles like a snake tail]. She has large, baby-blue optics. She is also equipped with a hoverboard, but she isn't allowed to use it inside.
Because of Decepticon activity, and worried for Lily's sake, Optimus has forbidden her from leaving the base, regardless if she was under the protection of another Autobot.
Returning to the aforementioned bond Lily and Optimus share, it is emotional and physical. Before Lily was resucitated as an Autobot, Optimus Prime placed a fragment of his sparks within hers, so he could feel what she feels and know something is wrong the instant it happens.
When she meets Jasper residents Jack, Miko, and Rafael, she is excited to finally see humans besides Agent Fowler.
Regarding Lily's "new" Autobot body, Alpha Trion built Amira as a sparkling and leaving her on the steps of an orphanage in Crystal City to be cared for. His reason: Primus himself told AT he needed to build a soldier from infancy, where she would soon grow and be raised to fight in the war for Cybertron. The ability to fight needed to already be in the body's programming. During a fight, Amira was fatally wounded and died later on.
Lily's fate had been entertwined from a prophecy on Cybertron, foretold to Optimus from Alpha Trion--"an alien child would become one of us and overcome evil". From Primus, AT told Optimus he needed to head to Earth so this alien child would be protected from Megatron's wrath.
The Decepticons knew of the prophecy as well and fear it involves Amira's power, so they set off to get rid of the prophesized child so they can continue their reign. They arrive to Earth before the Autobots do and were in pursuit of the child. They discovered Lily, who was only 4 years old upon their arrival, was the child they sought when Megatron "sensed" a familiarity between her and Amira. To get to her, they first needed to eliminate her parents. Starscream hunted young Lily and her mother. While Lily watched from the safety of the bushes, the Decepticon's first lieutenant slain Mrs. McElroy, then took off believing Lily had run away. Witnessing her mother's demise led to her development of PTSD and the nightmares.
The Autobots inform Lily's father as to why they were on Earth, and kept this hidden from Lily for her safety. They didn't want him to move from Jasper, so in case there was an emergency the bots could transport them swiftly to their base. Mr. McElroy managed to keep the secret about who truly killed her mother for the next three years, until one night the Decepticons made their attack. The Autobots intervened this time. Since their home was isolated and far from other neighborhoods, no other humans were nearby. Lily's father suddenly joins the fight, leaving Lily confused and alone in the house for her safety. However, when he is wounded, she rushes out into the heat of the battle, fearing she would lose her papa, too. But just as Mr. McElroy was about to tell Lily everything he hid from her, a Decepticon fires a blast at him, creating a hole in his chest, and he crumples to the ground before Lily's eyes. She becomes hysterical and slips into unconsciousness from the shock. She briefly awakens inside of a vehicle with a strange man in the driver's seat, telling her he was taking her somewhere she would be safe, and then slips back into unconsciousness.
She awakes in the Autobot base and is frightened of them at first, knowing they took part in the battle that took her only human parent left. She is so shaken up she vomits a bit before getting the chance to speak. Optimus provides her comfort, then answers any questions she had for him: who were they, what happened the previous night, what were those things they were fighting? Once her questions are answered, he assures her that they would keep her safe.
However, she constantly keeps following them; on one occasion she discovers Starscream is the one who murdered her mother, and another she ends up fatally wounded during a brawl between the Autobots and Decepticons, doomed to die if no immediate action was made. That action was to take the Autobot youngling's body and transfer Lily's mind into it. During said process, Optimus creates the physical and emotional bond they share. Lily freaks out when she awakens an Autobot, but calms down after a while when she feels comfort come from Optimus. She imagines the other bots to be her new family; Bumblebee becomes her brother, and Ratchet and Bulkhead become her new uncles. When Arcee and Cliffjumper arrive, they also join the family.
Lily seems to believe Optimus does not understand her pain of losing someone she loves. To prove her otherwise, he explains to her about her body's origin and about Amira, and how he believed her demise was his fault. At this, Lily finally understands and gives him a few words of wisdom her papa once told her. It is then they give each other what they have lost--a parent and a child.
One day, Lily wants to head outside because she is bored and accompanies Arcee. Unfortunately, the Decepticon warship, the Nemesis, arrives and attacks. Megatron, unaware Lily is alive and possessing the body, believes Amira is back from the dead and demands her to be brought to him. Arcee is knocked unconscious and Lily is taken prisoner. Aboard the ship, Lily cannot be track, therefore cannot be rescued. However, while she sleeps in her cell, a little birdie tells her what kind of power she possesses and uses it to her advantage. She uses it to escape, and plans on using it to seek vengeance upon Starscream.