Danielle Rosen is a guest character and is an Alpha with Empathetic Contagion.
Danielle is being chased by Isaac along with a 34 year-old man named Will who lived on the streets with her. After watching the man die at Isaac's hand, she escapes to a nearby hotel, where her father finds her. After Cameron shoots Isaac dead, she's taken back to DCIS office. Setting aside her animosity towards her father, she gives them an encrypted message meant for Red Flag members.
Later in the episode, after the team raids a Red Flag meeting, Dani comes home with Rosen. He talks to her about her powers and she shows him how her pain felt, after he asked for it.
Dr. Rosen is asked to address Congress about the "Alpha Situation," he surprises everyone involved by televising his speech—making the existence of alphas public for the first time. No one is more surprised than Stanton Parish who is actually in cahoots with Dr. Rosen's daughter.