Cuaron's camera (shot by the subtle, still beautiful version of Lubezki) isn't just a bystander, but an active, curious explorer of their lives and the places they visit. He does many extreme long takes, and he sometimes interestingly looks around, like he is the 4th person on the road trip. There are many times this becomes a feeling of uneasiness for the viewer, an awareness of invading privacy, looking where its forbidden. The reason for this is it creates a motif of cold separation from the characters, an uncomfortable feeling that I think they share towards one another. And though they have intimate moments, there isn't a genuine bond, and just as it appears to be forming (when the guys kiss), the next morning its gone.