I re-read this just recently!
It's Brothers and Strangers (http://www.fanfiction.net/s/2870484/1/Brothers-and-Strangers) by janissa11

Here's the link to the story on livejournal, but it's probably easier to read on fanfiction.net, as there's not always a link to the next chapter. Brothers and Strangers (http://janissa11.livejournal.com/?skip=20&tag=brothers%20and%20strangers)

Unfortunately, it appears to be an abandoned WIP as it hasn't been updated since 2009.