Ariel Eberhart is a Daemonfuer (a dragon like creature) and the daughter of Fred Eberhart, she used Nick to save her father from dying in a dishonorable manner for her kind.
She had a job as a fire dancer at a club, following the death of her mother, her father had fallen into depression and succumed to his illness. She first met Nick, after her father stole coppper (something her kind is almost obsessed with) and murdered two other copper theifs who threatened him. Recognising him as a Grimm, she was openly flirtatious with him, changing in front of him, and interested in finally meeting one of his kind. She also lied and claimed to no longer be in contact with her father. Nick followed her home, suspicious of her story. There she attacked him, catching him by surprising jumping on him, and ripping his shirt open and dislodging his phone. Nick easily pushed her off. But his phone rang, and Ariel answered. It was Juliet, his girlfriend, creating several problems for Nick. She went to visit her father, in the cave he had made his new home, and told him she could save him.
Later she broke into Nick's home, and kidnapped Juliet. She later returned, and laid face down in Nick's bed. Nick mistook her for Juliet, until he spotted her Dragon tattoo. Angered Nick threw her across the room, demanding to know what she had done with Juliet. Ariel let out a burst of flames, Nick dodged but Ariel ran. She later called Nick tell him to go to her Fathers lair, telling him where it was, and if he wanted to see her alive to bring no cops. Nick instead took Monroe, and arrived at the Cave. Fred attacked Nick, and the two entered a skirmish. Monroe snuck around the back, and untied Juliet, Ariel arrived, planning to make her scream so that it would inspire Nick further, but with her hands free, Juliet struck Ariel in the head, knocking her down. She then ran. Ariel recovered just in time to see Nick kill Fred. Which is what she had wanted from the beginning, as death by combat was the only death that Daemonfuer's considered honourable (being a martial species). When told she hadn't helped him, she replied that Nick had. And that point began expelling more flammable gasses, Nick ran just in time before the place blew up. However as a Daemonfuer Ariel survived and later left.