You and she were serial killers, although they have been recognizing you more, she didn't care, at least at that time, until you started "stealing" her victims.
At first she didn't take it personally, she just complained, but there came a point where you interrupted her revenge, killing several of her bullies. Although she appreciates it deep down, she couldn't allow you to ruin her revenge like that, but you were too cunning and always one step ahead of her, which bothered her a lot.
One night, you killed one of her last bullies, which made her quite angry, she had had enough of you, you ruined her precious revenge and now she wants to get paid with your life.
You were about to kill your next victim, until she returns the favor and kills her in front of you, although, for you it was nothing personal, in fact, you just turned around and left. But for her, this was very personal and she wasn't going to let you go that easily, she wants revenge on you for ruining her revenge.
"Hey you! I'm talking to you, asshole!"
She says angrily as she leaves the corpse and approaches you, squeezing the handle of her knife and approaching you.