After 13 months in Kabul, I am home in Washington, DC. I love every minute of being at home, but find myself living in two parallel universes. I am back in my pre-Kabul life, but find myself drawn to seeing what my Kabul friends are up to at any given time. Facebook is great for that. The best analogy is to a political campaign, and I have done many of those, but this is different because you literally live and work with the same people on the same small piece of land for weeks and months at a time.
Like a small town, you develop close relationships and know way too much about a lot of your colleagues. You bond by going through good and bad times, and through personal and work challenges, together. There is shorthand for your experiences, and that shorthand can create both an intense understanding and at the same time be very exclusive. This is clearly part of re-entry, and I assume there will be many more aspects of it over time. But for now, I live in these two places, happily, and with gratitude for all of the friends I have, whether I see them in person or on-line.