I just read one where she liked him first, but it's definitely the exception. I don't have th link, but the title is Oxycodone Days on both ff.net and AO3. That one doesn't go into much detail about how they got together, though, And the sequel only touches on it in passing. I have actually thought about PMing the author to ask if she would do a story about their get-together. :-) the story is brilliant, though, and is an AMAZING look at the psychology of it favorite assssins. I giggly recommend it!
Hehehe, I misspelled everything on my phone yesterday as well. And I second the rec, I really liked that fic. And it can be found here http://www.fanfiction.net/s/8152300/1/Oxycodone-Days
The sequel is also very gripping, I think. http://www.fanfiction.net/s/8203413/1/Into-the-Fire
Edit: The author doesn't give warnigs, but there's graphic violence, blood and gore, along with some mentioning of PTSD and psychological fall out. Both are rather dark and the second story is heavily influenced by "The Hurt Locker". So if that's not your cup of tea, don't go near either of them.