Write a twist story where a hero becomes a villian at climax.

Talia knew she was the chosen one; she had known since birth. She was reminded of her destiny every day. Talia had to be the one to take down the Winter Queen. The Winter Queen had been dictating the Earth for fifty years, waiting for the chosen one to try to challenge her. One Talia’s 16th birthday it was time for her to face the Queen. She was praised in each town she passed through. She was their only hope and seeing her made everyone happy. The queen’s reign would soon be over. However, Talia didn't see it that way. She was only a child after all. All this pressure was on her. If she messed up not only would the Queen win, but she would be shamed.
“It isn't fair, ” she thought, “Why did it have to be me?”
She felt this pressure to be perfect all the time. She was a skilled warrior of course, but only because she was trained since she was a child. She never had the chance for a real childhood. Finally, she reached the castle. There were no guards. Talia was confused. The Queen wanted to face her with no other influences. Talia’s heart raced. As she walked up to the Queen, who was turned admiring a painting, she could feel her hands shaking.
Before she could attack, the Queen turned around.
”I wouldn't do that if I were you.” She stated.
“ What?" Asked Talia, confused.
“ Because it's not what you really want. It's what everyone wants for you.”
“You don't even know me!” Talia screamed.
“ No, I do know you. Because I was you.”
Talia stood, confused as the Queen took off her crown and walked towards her vanity.
“ I was twelve when my father died. He had been killed by one of your people. I had no other choice but to become queen, ” she looked at herself in the mirror and stopped for a moment “I'm over it, obviously. I'm not a little girl anymore. But at that time, I wanted to revolt completely. It wasn't fair, but there wasn't anything I could do. You, on the other hand, have a chance.”

“I do?” Talia asked, entranced in the Queen’s story.
“ Of course, you could join me.”
“ I could never!" she spat.
" But you could. Think about it. No one telling you what to do, and you could have limitless power. We could rule together.”
”promise?”
“promise.”
And with that, the two set off with the queen’s army to defeat the last kingdom the Queen needed to defeat for the complete rule. Talia’s people. Talia led the Queen to all if the secret paths, attacking small towns until the deed was done. Back at the palace, Talia thought about what she had done. All for a little power; a little piece of her own destiny; a small revolt that wasn't so small.

Okay so that's definitely not a finished piece, but you can go ahead and edit it as you see fit.