So, I want you guys to take this with a grain of salt, because this is just my understanding of the story that I got from MTL.
What I’m about to say is mostly from chapters 6, 7, and 8. But first, let’s start with some basics.
Is Lily a pirate? Yes. But from what I understand, she mainly attacks other pirates. Also, she’s working with Al’s tutor,
who we see in Chapter 1. In a flashback, Lily calls the tutor “Pi.”
What happens in chapters 6, 7, and 8 revolves around Lily stealing some classified documents about the Barant Pirates. Al was chasing them, and in order for him to be free from work, Lily decided to handle them herself.
Anyway, to get the documents, she knocks Leo out, takes her uniform, and disguises herself as her (Chapter 6). Then she steals the documents from Al.
Using the information in the documents, Lily and her pirate group attack one of the Barant Pirates’ ships. While Lily is fighting, the tutor is watching and reading the documents that Lily stole, and he says that Al is going to get mad about all this. It’s worth noting that Lily is still disguised as Leo.
At the end of Chapter 7, we see a pirate rushing to inform the boss of the Barant Pirates that one of their ships got attacked. And at the end of Chapter 8, we see that the boss is looking for Leo (Lily in disguise), because the information they have is that they were attacked by a navy woman with black hair who is missing a piece of her ear.
I’m not sure about the timeline, but it seems that while Lily was attacking the Barant Pirates’ ship, Leo was found. She had no external wounds, but she had a pretty bad fever from being left outside. Al then realizes what happened and goes to look for the Barant Pirates’ ship. He finds it, but Lily has already left. They treat the survivors and arrest them.
Later, at Al’s home, Lily shows up to hang out. She attacked the Barant Pirates so that Al would be free from work and have time to spend with her. As expected, Al is furious. He attacks her and tries to persuade her to stop being a pirate.
This is where we get Lily’s motivation. While she’s on the floor trying to reach for her sword, we see a flashback of her training with the tutor when she was younger.
In the flashback, the tutor tells Lily that he understands why Al joined the navy and why Lily wants to be a pirate, but he doesn’t think her choice is the right one. Becoming a pirate means becoming Al’s enemy. He asks if she has the resolve to be hated by Al.
And here is Lily’s reply:
“…To be hated… no, I don’t want that. But even more than that… what I realized I hate is living in a world without Al. If we can’t be together, then at least I want to fill Al’s mind with me. If nothing else, I want to fill it completely with me. If it’s for that… I don’t mind even if I’m hated. No matter what form it takes, I just want Al to notice me. That’s why I’m taking up the sword. Because the sword will connect Al and me.”
Then the tutor says:
“But Lily, what about Al’s feelings? Al joined the navy because he was thinking of you. He chose that path to protect your future and happiness. Can’t you understand that kindness?”
And Lily responds:
“…Yeah, I know. I understand. But still, why is it that even though he's being kind to me, I feel this lonely? Ever since that day*, I’ve been lonely all this time. I know Al is kind, and I know he cares about me. But that kindness isn’t kind to me. If that kindness only ends up making me feel lonely, then I’d rather he fill me with pain instead.”
*That day refers to when Al left to join the navy.
Needless to say, Al can’t convince Lily to stop being a pirate, even when he says that if she gets caught, she’s going to be hanged. Al asks if doing what she’s doing makes her happy, and she says yes. Then a devastated Al tells Lily to do whatever she wants.
And Lily says, “Thank you. Then… see you, Al. Let’s play again.” And she leaves.
So yeah, Lily is very twisted. She can’t deal with the loneliness she feels when she’s not with Al. And the thing is, I can’t sympathize with her at all. She’s too selfish. In stories like this, I think you’re supposed to sympathize at least a little, but I just can’t. I suppose what I’m feeling is exactly what the author wants me to feel… but I really don’t like it because I can’t connect with Lily.