Root can't help it, it's basically compulsive to flirt with violent women, and seeing Claudia tear out a man's throat with her teeth had certainly helped place her in the 'woman' category after learning her real age. She experiences mostly mental rather than physical attraction, anyway. The flirting is fun in its own right, even if it doesn't go anywhere.

"I could describe it to you if that's something you're interested in," she suggests, tone sly. Root reaches up as she walks and pulls the pins out of her hair to let it down from its secretary bob, and it falls down around her face in waves. This part is not intentional flirting; she's just literally letting her hair down since her charade is over with for the evening.