PLOT IDEA

Lìlli was a young girl, who had been serving in Odin's palace in Asgard for as long as she could remember. She grew up side-by-side with the two Princes, Loki and Thor, and even almost became friends with them.

Almost.

At age 7, she was approached by an ex-soldier named Malloc, who had last served as a warrior way back in the Battle of Jotunheim and was now no more than a glorified drunkard. Malloc told Lìlli her terrible secret, which shut her off from the rest of Asgard. Apparently Malloc had been the one who had brought her to the palace when she was still a baby, unable to raise her himself, and because of this he, and he alone knew her true origins, and her secret.

No, Malloc was not her father. (Nor was he Darth Vader, sorry.) But he knew who she was, and knew her potential abilities.

After Malloc had told Lìlli her secret (and no, I'm not telling you what it was), the young castle servant distanced herself from everyone, afraid to hurt those she cared about and scared that somebody would discover her secret.

Malloc, even though he officially had nothing to say over her because she served in the palace, ordered her around and threatened that if she disobeyed him, all of Asgard would know her secret within hours.

Perhaps Lìlli would've stayed as she was, controlled by fear and blackmail, if not for one thing.

One event that changed her life.

Thor's banishment.

Thor, the little blonde boy who she'd had a crush on since she was little. With whom she'd listened to stories about scary Frost Giants when she was still too young to help out in the castle. The boy that she'd continued to serve as he grew up, and had slowly became more and more fond of.

That Thor, was gone.

Lìlli hid herself in the library (she didn't have her own room), planning to stay there for a day, impulsively not caring what Malloc said or did. If he revealed her secret, so be it. The only one who came into the library was Loki, and he tried to chase her out, but gave up after a few attempts; clearly also exhausted from the shock of his brother's banishment.

When Lìlli showed herself the next day, she expected to be arrested and killed straight away, as Malloc would've told Odin who she really was by now. But Malloc had chosen not to tell anyone Lìlli's secret yet, and Lìlli wondered if he would really carry out his threat if she disobeyed him. After all, the moment he did, he would lose all control over her.

As time passed, the Odinsleep happened, as well as some other important events that can be incorporated into the book if it ever gets written.

In any case, Lìlli slowly started appreciating Loki more. She'd never paid much attention to him before, because all her attention had been focused on Thor. Loki and Lìlli developed a relationship which could almost be described as 'friends'. Lìlli completed small tasks in and around the library, such as dusting off shelves and putting away books, and in exchange Loki occasionally let her read in the library during her working time, claiming that she was 'researching' for him because he knew she loved to learn.

However, through it all Lìlli made sure to keep herself away from actually becoming friends with Loki. Even if she thought Malloc wouldn't tell anyone her 'secret', she was still afraid to hurt people. So they remained at 'acquaintance' terms, although Lìlli wished she could at least be friends with the Prince. But she refused to allow herself to put Loki in such danger. Not that he was at all defenceless, but because she was afraid of her own capabilities.

And because she knew that if anything happened, if she lost control for whatever reason, he might have to fight her. If that happened, it would be better if he didn't see her as someone he loved.

Then Thor returned out of nowhere, having stopped Loki's evil plans with the Warriors Three and Lady Sif, not to forget Jane. Loki "fell to his death", not really but you all know what I mean.

Lìlli cried, not knowing whether she was crying because Thor was crying or because she cared for Loki more than she'd allowed herself to believe.

TIME SKIP

Over time that followed, Lìlli had grown closer to Thor, who in turn became good friends with Lìlli in the same sort of way that Lìlli had grown closer to Loki when Thor had been gone. It wasn't the same however, especially because now Lìlli knew something she hadn't known before — Loki was a Frost Giant. It was revealed to the Asgardian public shortly after Loki's supposed 'death', and shocked many.

For some reason, it hadn't scared Lìlli as much as it should've, but served to distance her from becoming anything other than friends with Thor. Malloc died, ironically because of an overdose of alcohol.

Everything seemed to be going smoother now — Loki was dead, and Lìlli, like everyone else, had mourned his death. Thor was a friend, and would never become more than that in Lìlli's eyes again. She'd been promoted to Thor's personal assistant, and her insight in battle tactics and advice was extremely valuable to the future King of Asgard.

Lìlli even summoned enough courage, shortly after Malloc's death, to tell Thor her secret.

He took it with mild surprise; nothing could surprise him much after finding out that his brother had been a Frost Giant. The Warriors Three, Lady Sif, the Allfather and the Queen were informed of Lìlli's secret for 'safety reasons'. But to the rest of Asgard, the secret would remain what it was — a secret. 

And then Loki was found to be on Midgard.

There was chaos in the Asgardian Palace, and it was soon decided that Thor would be sent to Earth because he had experience with the Midgardians' ways. Lìlli insisted on coming with, and Thor eventually agreed to let her come.

Thor left Lìlli on the ground as he and Mjölnir went after the jet which he knew to contain Loki. He landed on the wing on the jet, subtly taking Loki out, and addressing him back on the ground, only to be interrupted by Stark and Rogers. Lìlli watched in awe as they battled, only to drag herself away from the battle in attempt to find Loki.

Whether she found him or not is up to the author.

...

And that's as far as I got. From here it's up to you to decide how it continues, unless I do end up writing it. A few further ideas I had were —

~ Lìlli calls herself Lily when on Earth because it's easier for 'Midgardians' to spell. I personally just pronounce both the same, but otherwise you could say the pronunciation was easier too.

~ It's up to whoever writes this whether Lìlli ends up falling in love with Loki or not, but it's a possibility. Or maybe she'll fall in love with somebody else, who also happens to fear their own abilities...

~ I have an idea as to what  exactly Lìlli's 'secret' is/was, but I chose not to put it here in case I do write it, because it would be a bit of a spoiler. Obviously, if you want to attempt to write this plot out yourself, I could tell you in a private message or something.

What do y'all think?