This is so lovely, Hannah! I hadn't really ever considered Katie/Harry before as I'm more of a Harmony shipper, but you and Jess are slowly converting me :).
It was so wonderful how they bonded over both cheating death, and how the only person who could really understand what Katie had gone through was Harry. You showed how they needed each other to fix each other - which I love in a relationship ;)
The writing was beautiful, and you write Katie so well in all of your stories so the characterization was gorgeous. This entire one-shot was just amazing, and I like how you expanded it.
I'm not much of a fan of Harry with anyone other than Ginny, but you pulled this off really well.
I think the best thing about this is the dialogue - it's hard to tell a story mostly through dialogue, and yet Harry and Katie's conversation flows really naturally.
The first sentence is fantastic - you immediately establish the character and the emotion she's going through and give a hint of sense of place (just a nitpick - you wrote her eyes tight shut against the icy windy - I think you mean "wind"). You really created empathy with Katie and I felt like crying about all the horrible things that had happened to her.
It was a very moving and well-written story, Hannah.
That was amazing! It was beautifully written and powerfully emotional in all the right ways. I liked it a lot.