This is Candybrine aka Elena. A little backstory:

Back when she was only eleven years old, Elena's village was attacked and burned down by Herobrine. When she met Herobrine leaving her destroyed village, she tried to attack him with her wooden sword. Of course, it didn't hurt him at all, but she was certainly brave for trying to hurt him. He started to fly away, but she took out her enchanted bow and shot him in the leg. He threw the arrow back at her, but she just kept trying to shot him. When he started to get farther away, she mounted her horse and chased after him. He started to get annoyed and threw a fireball at her and she narrowly avoided it. He continued to fly away and Elena started to yell at him.
"Come back here! I'm gonna kill you!"
He flew down to her and kicked the horse out from under her. He took out a diamond sword and killed the horse. Then, he summond a fireball and threw it at Elena. This time she had no time to dodge. She went unconscious and thought she was done for. To her surprise, she woke up in a comfortable bed. She tried to get up, but her body was consumed by pain. It must have been from the fireball directly hitting her. She saw something to her right and barely managed to turn her head to see Herobrine towering over her.
"You're an idiotic little girl."
"Where am I?"
"My mansion. I thought you should at least live until you know who I am."
"I already know you're Herobrine."
"If you know who I am you should know I'm Immortal. Yet, you tried to kill me."
'You destroyed my village! I couldn't just let you get away with that!"
"I have an idea."
Herobrine covered her eyes and used his powers to put her to sleep. He put a curse on her that gave her part of his power. His power came with a price though. She wouldn't be able to control it. She would kill people without mercy and burn down anything she could whenever she lost control. That would be hilarious when it first happened, to him at least. He opened the window and threw her out, that would activate her new powers to save her life. Before she hit the ground she suddenly woke up and her eyes started to glow white. She stopped in mid-air and flew back up to the room. When she her eyes stopped glowing she turned to Herobrine who was laughing crazily.
"What did you do to me?"
"I gave you some of my power. Your gonnna be a killer like me now!"
She threw a punch straight at his face, but he easily blocked it. He pushed her hand away and smirked. 
"You have nowhere to go now. You should stay a while, since you would probably destroy everything if you go anywhere else."
Angrily, she stayed with Herobrine in his mansion. He taught her how to use her powers, but she never had total control over them. They created an alternate personality for her that she called Candybrine. After years living with Herobrine, she started to warm up to him, seeing how he couldn't completely control his powers either. He chose when he lost control though. Eventually she forgot about her old life as the village girl Elena and started to identify as her alternate personality Candybrine. Then, one day Herobrine suddenly vanished. The mansion was completely empty, not even a silverfish could be found, but that wasn't such a bad thing. She decided to look for Herobrine, but she didn't go outside the mansion that often. Everything was pretty strange to her. When she first set out though, it was night, and she ran into an enderman. Unknowingly, she stared it straight in the eyes and it attacked her. She flew away and skeletons started to shot at her. This would take a while to get used to. She would have to find some people to help her, if they trusted her. She knew that would never happen though.

Sorry, got a little carried away with the story. Thanks for reading all the way if you did. <3 P.S. This was all thought of on the spot.