If you would ask anybody of the Bella's who Denise was you didn't get a simple answer. She was someone who kept quiet. She was a good singer. But not someone who was a centre of attention. She was visible and invisible at the same time. Nobody knew who she was or what kind of hobbies she had. Not even Cynthia Rose who was her ex girlfriend.
Denise kept to herself. And she had a good reason for that. Denise was a trained assassin. She came from a family of assassins. And she was hired to kill the Bella's. It wasn't that she hated the Bella's. She came to really like them all, but the money she was paid was just too good to decline the offer.
She had techniques that made her different than any other assassin. Falling in love with Cynthia Rose was one of those techniques. Just like joining the Bella's. She needed to get in the Bella's to learn their routines. You see killing nine people at once was not an easy task. She needed to find out what their routine was and what the best way was to kill them all at once. And without getting killed herself. Just a few injuries for herself to keep the story credible when she would be the only survivor.
She had planned it all. She had made a bomb and hide it in the Bella's tour bus. When they would go to an performance she would get out off the bus. She thought that nobody had seen her. But she was wrong. Apparently Lilly had found out. She was in shock when the Asian girl went in her room to arrest her.
Yes, she had some explaining to do.