When she asks him the question, they're standing on the roof of one of London's finest townhouses, her silk gown ripped to the knee, the stolen sapphire barrette brazenly pinned atop her curls.
"Holmes-" The wind tugs at the edges of her clothing and hair. She takes a step back, drawing closer to the stone rooftop's rain-gutter boundary. "Why do you love me?"
They're so very high up; distracted, hoping to distract her as well, he answers honestly. "Because I have no idea what you'll do next."
Irene laughs- and, light as an angel, takes a running leap off the edge.
When he asks her, they're standing in an alleyway next to a broken window at ankle-height. Ideally, he'd like to get her away from the window and into purer air, perhaps even out of London entirely, but she looks so pale, and she hasn't stopped trembling- he'd really rather not have to deal with her collapsing on him. What was she thinking, letting Moriarty trick her into an enclosed space like that? All right, so the telegram, once deciphered, had said something about "Holmes" and "a deathtrap," that, for his mental health, he'd decided not to decipher fully... nevertheless. Just... nevertheless. Bloody carbon monoxide poisoning- if he hadn't heard the slight hiss of escaping gas- why could she possibly have-
The question doesn't come out as he intended. Between brain and clenched jaw, a transformation takes place: "Goddamnit, woman- why do you love me?"
Tears still cling to Irene's eyelashes as she smiles up at him. Shaking her head, she whispers, "I wish I knew."