Regarding that "Fine!"
My experience has also been that it's used to say, "You might be right, and hence the discussion will now cease." In my own house, and my wife and kids will attest to this, where it's generally considered that I don't even have a temper, I'd heard that "Fine!" thrown around till it hit my own tipping point, and I bellowed out one day, "NO MORE CRABBY FINES!"
Dead silence in the house. "Fine!" in that context was never heard again. The kids still quote me to this day. In fact, if they ever wander to this thread and find this post, they will have me pinpointed. It's one of those signature things for the family.