4 ideas
Gurb takes the form of pop singer Marta Sánchez and vanishes into the city, and the commander, disguised as figures such as the Count-Duke of Olivares and Gary Cooper, searches for him while keeping an hour-by-hour log. The log records him being run over by vehicles, losing his head down a drain, eating churros compulsively and slowly adopting the human habits he set out to study.
An observer who knows no local conventions describes everyday behavior literally: traffic, queues, bar talk, courtship, bureaucracy. Stripped of their assumed purpose, routine practices look absurd. What the insider sees as common sense turns out to be a pile of unexamined, often irrational rules.
The narrator records chaos in the flat, precise format of an official hourly report, with timestamps, measurements and procedural notes. The gap between rigorous form and ridiculous content produces the humor. The same structure also shows a methodical mind being gradually worn down by an environment that ignores method.
The alien can copy any human's exact body, yet he keeps failing to pass. Belonging depends on tacit behavior, timing and shared habits, not on looking right. Assimilation happens only by accident, as he absorbs appetites, attachments and routines until he no longer wants to leave.