O'Brien wrote prodigiously during his years as a student at University College Dublin (UCD), which was then situated in various buildings around Dublin's south city centre (with its numerous pubs and cafés) and thus considerably more bibulous than in its modern suburban campus. There he was an active, and controversial, member of the well known Literary and Historical Society. He contributed to the student magazine ("Fair Play") under various guises, in particular the pseudonym Brother Barnabas. Significantly, he composed a story during this same period titled "Scenes in a Novel (probably posthumous) by Brother Barnabas", which anticipates many of the ideas and themes later to be found in his novel, "At Swim-Two-Birds". In it, the putative author of the story finds himself in riotous conflict with his characters, who are determined to follow their own paths regardless of the author's design. For example, the villain of the story, one Carruthers McDaid, intended by the author as the lowest form of scoundrel, "meant to sink slowly to absolutely the last extremities of human degradation", instead ekes out a modest living selling cats to elderly ladies and becomes a covert churchgoer without the author's consent. Meanwhile, the story's hero, Shaun Svoolish, chooses a comfortable, bourgeois life rather than romance and heroics: