During one battle of many on Bajor, during the Cardassian occupation, a resistance cell found one building especially difficult to capture. A Cardassian man and woman, working as a team, absolutely fought to the death to protect their corner of the facility. It wasn't until the aftermath of the battle when one of the Bajoran resistance members thought to investigate, expecting to find a very important piece of technology, or information vital to the Cardassian government. What he found was a Cardassian female infant.
Having just lost his own family to battle, this Bajoran might have been angry and vindictive, deciding that it served them right to have to go through what he did. He was more compassionate than bitter, though, and felt an echo of the same sorrow he had when his own family had died. He took the infant back with him, with a half-formed notion of raising her on his own.
He soon discovered that he could not do that. Though the Bajoran people on the whole were not inclined to punish the children for the sins of their parents, there were a couple of angry Resistance members who couldn't see past the blindness of their own hatred. One of them tried to strike the baby with a killing blow. He blocked her, breaking his own arm in the process. Understanding quickly that he could not keep the infant in that place, he came upon a stroke of luck when he found a small Vulcan team landing to provide humanitarian aid to the Bajoran people. He explained the situation to the team, and one couple agreed to take the girl.
He told them the girl's name, and they accepted it as hers. He was certain he knew her birth name, because it was inscribed on a tag within her clothing. And so it was that Lina was named after a large Cardassian maternity and infant supplies manufacturer.
The Vulcan couple were braced for a very difficult job, but they were pleasantly surprised. Lina was very anxious to please, and no more explosive in her temper than most Vulcan children, who were born in the "barbaric state" for which Vulcan discipline provides a barrier. Having traveled to many different worlds, her adopted parents were aware that she could not be made into a 'perfect Vulcan', but they encouraged her to take on the culture as her own. She had a reasonably good childhood, as Vulcan discipline in the schools kept other students from bothering her beyond the periodic unfriendly glance, but she had very few friends.
Lina developed a very forgiving and compassionate nature, and an interest in her surroundings. Soon her Vulcan parents found that their home was going to be a very different place from that which they'd pictured when they'd first designed it. They needed to incorporate first a bathtub, then a small pool, then a larger pool for their 'child', who tolerated heat well but suffered in the very dry air. Then she started bringing injured wildlife home, tending them and keeping them in all sorts of carefully-chosen cages until they had healed and could be set free. Not a few of them ended up staying nearby, and she ended up with many more pets than friends.
Her father, frustrated by her lack of interest in logic games and puzzles, followed her into her room on one occasion and noticed her bureau top filled with rocks and sticks. Putting aside his initial emotions as flawed, he asked her about them and discovered that she readily "saw" a mountain in a rock, a tree in a stick, and enjoyed creating her world in miniature. He started her on simple models, many of which were hurled across the room in her frustrations, until she began to thoroughly enjoy the hobby. By her teenage years, she was more interested in building a ship in a bottle than playing chess, and he simply allowed her to express herself in this manner.
Lina chose Starfleet because she was hoping that, among all the myriads of unusual races there, she would be better accepted among her peers. Unfortunately this did not happen. She endured harsh insults and periodic violence, sometimes from her fellow students, and sometimes from the surrounding city. She stubbornly refused to complain to her teachers, judging accurately that their heavy-handed approach would cause resentment rather than peace. Over time, she found that by simply doing her best and avoiding violence when possible, she could minimize the attacks and get her work done.
At first her teachers thought she'd be a scientist, but she ended up with greater interest in the medical field. After a great deal of thought and despite a realistic appraisal of how others would react to her very presence, she chose to enter Starfleet Medical anyways. There she had one of very few positive social experiences in her life, as a small group of Bajoran medical students took her into their group as something between "mascot" and "pet". She allowed herself to fall for their silly pranks, understanding that they did not mean to hurt her, and they introduced her to Bajoran culture. Lina was both horrified and delighted to find that she enjoyed eating meat. The best thing they did for her, though, was protection from those who might have attacked her again. Once word got around that she was "part of" their "group", she was largely left alone.
Following her interests, Lina took all the classes she could involving xenobiology, subliminally seeking out races that had no inherent distrust of her, and surgery, putting her miniature-building skills to work with very careful and accurate manipulation of tools in tiny, tight spaces. She became especially comfortable with keyhole surgeries, and though she did nothing groundbreaking or startlingly clever, she passed with very good scores in her specializations.