I never knew I had a twin sister until I met her at Camp Half-Blood. Her name was Bianca Di Angelo, and she was the daughter of Hades, the god of the underworld. She had been living with her brother Nico, who was also a son of Hades, in a casino that stopped time. They had been there since the 1940s, when their mother died in a hotel fire.

Bianca and Nico were brought to the camp by a satyr named Grover, who was looking for the next great prophecy. He thought they might be the children of the Big Three, the most powerful gods in Olympus. He was right, but he didn't know there was another one.

That's where I come in. My name is Lila Di Angelo, and I'm also a daughter of Hades. I never met my mother, or my siblings, or my father. I grew up in an orphanage in New York, where I learned to survive on the streets. I had a knack for finding things, especially shiny things. I also had a strange ability to talk to the dead, which freaked me out.

One day, I was chased by a monster that looked like a giant dog with three heads. It cornered me in an alley, and I thought I was going to die. But then, a girl with dark hair and green eyes appeared out of nowhere and stabbed the monster with a bronze knife. She told me to follow her, and she led me to a place called Camp Half-Blood.

There, I learned that I was a demigod, a half-human, half-god child. I also learned that I had a twin sister, Bianca, who had just joined a group called the Hunters of Artemis. They were immortal maidens who served the goddess of the hunt. Bianca had given up her life at camp to join them, and she didn't seem to care about me at all.

I felt hurt and angry. Why did she abandon me? Why did she choose to be with strangers instead of her own family? Why did she get to have a brother and a father, while I had no one?

I decided to prove myself to her, and to everyone else. I wanted to show them that I was a worthy daughter of Hades, that I was strong and brave and loyal. I wanted to make them proud of me.

That's why I joined the quest to rescue Artemis from the Titan Atlas. That's why I faced dangers and monsters and enemies along the way. That's why I risked my life for my sister.

But nothing went as planned. And nothing would ever be the same again.

The quest was supposed to be simple. We had to find Artemis before the winter solstice, when she had to attend a council meeting of the gods. If she didn't show up, there would be war between Olympus and the Titans.

We followed the clues that Artemis had left behind. We traveled across the country, from Washington D.C., where we met her lieutenant Zoe Nightshade, to San Francisco, where Atlas was holding her captive.

We met allies and enemies along the way. We fought against skeleton warriors, giant scorpions, Nemean lions, and more. We also met some friendly creatures, like Apollo's sacred cows, Hephaestus' automatons, and Pan's wild nymphs.

We also learned more about each other. Zoe turned out to be one of the original hunters of Artemis, who had been alive for thousands of years. She had a grudge against Hercules, who had betrayed her long ago. She also didn't like me very much, because she thought I was too reckless and impulsive.

Nico was fascinated by mythology and history. He knew a lot about the ancient world and the gods. He also had a dark side, which he tried to hide from everyone. He could summon skeletons from the ground and control shadows. He also had a crush on Percy Jackson, the son of Poseidon who led our quest.

Thalia Grace was another daughter of Zeus, who had been turned into a pine tree for seven years by her father to save her from dying. She had recently been revived by a magical fleece that Percy had brought back from his previous quest. She was brave and fierce, but also stubborn and proud. She wanted to be the best at everything, and she often clashed with Percy over leadership.

And then there was me. Lila Di Angelo, the daughter of Hades who nobody wanted or cared about. The daughter of Hades who wanted to prove herself to her sister and her father. The daughter of Hades who would do anything for her family.

But what if my family didn't want me? What if they hated me? What if they were better off without me?

These were the questions that haunted me as we approached our final destination: Mount Tamalpais, where Atlas was waiting for us with Artemis and a surprise that would change everything.

As we climbed the mountain, I felt a cold wind blowing in my face. It was like the breath of death, and it made me shiver. I looked around and saw that the landscape was barren and bleak. There were no trees, no flowers, no animals. Only rocks and dirt and snow.

I wondered if this was what the underworld looked like. If this was where I belonged. If this was where I would end up.

I shook my head and tried to focus on the task ahead. We had to find Artemis and free her from Atlas, who was holding up the sky on his shoulders. He was the leader of the Titans, the ancient enemies of the gods. He wanted to overthrow Olympus and bring back the age of chaos.

We had a plan to stop him. We had a weapon that could defeat him. We had a prophecy that guided us.

But we also had doubts. We had fears. We had secrets.

Zoe had a secret. She was dying. She had been poisoned by a dragon's tooth during our fight with the Nemean lion. She didn't tell anyone, but I could see it in her eyes. They were dull and tired, and they had lost their sparkle.

She also had a secret that she didn't even know herself. She was the daughter of Atlas, the Titan who held up the sky. She had run away from him when she was young, and joined Artemis as her first hunter. She had changed her name and her appearance, and tried to forget her past.

But her past caught up with her when we reached the peak of the mountain. There, we saw Atlas holding Artemis captive under a huge metal frame that supported the weight of the sky. He looked like a giant man with silver hair and eyes, wearing a suit of armor that glittered in the sun.

He also looked like Zoe.

He recognized her as soon as he saw her. He called her by her real name: Zoë Nightstar, his daughter.

She gasped and backed away from him. She denied that he was her father. She said that he was a monster, a traitor, a tyrant.

He laughed and said that she was just like him. He said that she had inherited his strength, his courage, his ambition. He said that he was proud of her, and that he wanted her to join him.

He said that he had a gift for her: a place among the stars.

He pointed to the sky, where we saw a new constellation forming. It looked like a girl with a bow and arrow, surrounded by stars.

It looked like Zoe.

Atlas said that he had arranged this for her, as a reward for her loyalty to Artemis. He said that he knew she loved the stars more than anything else, and that he wanted to give her what she always wanted.

He said that all she had to do was take his place under the sky, and let him go free.

He said that it was her destiny.

Zoe looked at him with horror and disgust. She said that he was lying, that he was trying to trick her, that he didn't care about her at all.

She said that she hated him, and that she would never join him.

She said that she would rather die than become one of his stars.

She drew her bow and shot an arrow at him.

But it bounced off his armor and hit her in the chest.

She fell to the ground, bleeding from her wound.

She looked at me with pain and regret in her eyes. She whispered my name: Lila.

She reached out her hand to me, as if asking for help.

I ran to her side, ignoring Atlas' laughter and taunts. I knelt down next to her, and took her hand in mine.

I felt tears streaming down my face, as I saw how pale and weak she was.

I told her not to worry, that everything would be okay, that we would save her.

But I knew I was lying. I knew she was dying. I knew there was nothing I could do to stop it.

She smiled faintly at me, and squeezed my hand gently.

She told me that she was sorry, that she should have been nicer to me, that she should have treated me like a friend.

She told me that she was proud of me, that I was brave and loyal and strong.

She told me that I was a true daughter of Hades, and a true hunter of Artemis.

She told me that I mattered to her.

She told me that I mattered to everyone.

Then she closed her eyes, and breathed her last breath.