Alcoholism is at the center of Brideshead Revisited and essentially destroys a beautiful, charming young man. Of course, the alcoholism itself is driven by a slew of other problems, namely family and religion. The young man in question turns to the substance as a means of escaping, retreating further and further into self-imposed isolation by means of intense bouts of drinking. As is said many times in the novel, alcohol is used primarily as an escape.
Each character’s love for Sebastian is tested – and either proved or disproved – through his or her reaction to his alcoholism.