Danielle Sophia Rosen was the only child of Doctor Lee Rosen, and the reason he became an expert for the Alpha phenomenon. She was an Empathetic Contagion, with the ability to sense, absorb and share emotions. Her powers often caused her physical pain.
When her father found out about Dani's special abilities, he made a mistake that permanently damaged their relationship. Danielle's mother, Sarah, was going to leave Lee, and he used their daughter and her powers to make her stay. Dani absorbed the negative emotions all around her, leaving her in constant agony.
When she couldn't take it any longer, Danielle ran away. She tried to cope with the downside of her powers by self-medicating, using opiates and anti-convulsives.
As an adult, Danielle eventually reconnected with Lee, although their relationship remained tense.
Through her father, she met Cameron Hicks. She fell in love, and while he claimed to love her too, it's possible that he felt drawn to her because the effects of her ability reminded him of the highs he experienced under the influence of alcohol and pain meds.
Danielle was killed by Stanton Parrish in an explosion in 2012.