An hour into the drive, we'd already settled into roles.

I was the driver, navigating the continuous switchbacks up the northern Thai mountains in our little rental car. Mel was booking our next moves — flights, buses, hostels. And Cat acted as navigator and tour guide, suggesting we stop at a waterfall to climb and later, a stunning canyon for sunset.

Almost instantly, we were a team. Soon, we felt like family.

We'd known each other a combined week or so at that point. Isn't it funny how travel often forges bonds that seem illogically strong?

This story had begun 2½ years earlier, when I met Mel, who is from Belgium, in Barcelona.

We were staying at the same Airbnb, hit it off instantly and ate and laughed our way around the city. She helped me pick out a tattoo, which I stupidly had inked in an alleyway. Later, she got her own tattoo to commemorate the three days we spent together. We swore we'd have a reunion.

In February, we did — meeting in Bangkok with the intention of exploring Southeast Asia — and promptly became a trio: Cat, a solo traveler from London, seamlessly merged with our plans and came with us to Chiang Mai and then to Pai, where we gazed over hazy mountain valleys, ate bowls of noodles in the street, and (accidentally) drove through a pedestrian-packed market when our GPS led us astray. Now? We have a group text going — chatting almost daily.

How can such closeness happen so quickly? My theory is that when making friendships on the move, we're forced to skip a few steps. Suddenly, you're with an individual 24/7. You see how she deals with conflict and makes decisions. Especially when abroad, you are compelled to rely on each other. You complement each other's strengths — or you don't.

By the time we left Pai — Cat for an elephant refuge, Mel and I for Cambodia — we knew we were friends for life.

Amelia Rayno covers food and travel for the Star Tribune. Follow her on Twitter and Instagram: @AmeliaRayno