The first 15 minutes of “End of the Century,” the debut feature film from Lucio Castro, flirt with banality, hard. Och o hits an Airbnb on the Barcelona coast and gets up to not much at all. He dines alone, drinks beer, visits the beach and exchanges glances with a guy about his age. Eventually he calls to the fellow from his balcony. He comes up. Introductions — the fellow is named Javi — flirtation, exploratory kisses and sex ensue.

What does not ensue is a gay variant of “Before Sunrise” or “Brief Encounter,” as much as the movie seemed to have been heading for some such thing. The measured ordinariness of its first section has been a sly setup for a poetic film that handles narrative as a kind of scarf dance.