As Death on the Nile explains, there is a history between Hercule Poirot (Kenneth Branagh) and Bouc (Tom Bateman) that extends beyond their meeting in Egypt. A sequel to 2017's Murder on the Orient Express, the long-awaited Death on the Nile retcons the famed detective Poirot's history with Bouc, bringing the character back for another adventure.
In Agatha Christie's novels, Bouc is only included in Murder on the Orient Express. Described as a short and stout man, he is the director of the company that operates the train, as well as a friend of Poirot's. Bouc is able to get the detective a second-class cabin on the train. However, in order to accommodate for his space later, Bouc moves to a second-class cabin, giving Poirot a first-class room with more space. After the murder of Edward Ratchett, Bouc aids Poirot in helping him find the killer in Murder on the Orient Express. While his contributions are minimal, he makes sure no one leaves and that justice is served.
Although Bouc has no role in the original Death on the Nile book, he returns in the 2022 Poirot sequel. While his role in Kenneth Branagh's Murder on the Orient Express remains mostly identical to the novel, Bouc is re-introduced as one of the guests invited to the marriage celebration of Simon and Linnet Doyle (Armie Hammer and Gal Gadot) in Death on the Nile. In a significant change to the novel, Bouc replaces the character of Tim Allerton, as Michael Green's screenplay has him adapt Allerton's entire arc. After the events of Murder on the Orient Express, Bouc explains that his uncle removed him from the train because he didn't help much to solve the murder. Since then, he has spent his days with his mother Euphemia (Annette Bening), visiting different places and helping her with her art. Bouc heralds Poirot as the greatest detective of all time and provides him with a rundown of all the guests as well.
As Death on the Nile progresses, Bouc is shown to be in love with Rosalie Otterbourne (Letitia Wright), the daughter of Salome Otterbourne (Sophie Okonedo). In Agatha Christie's Poirot novel, Tim Allerton's mother is overjoyed to hear of the union; however, in the movie, Euphemia doesn't approve of the relationship and thinks Bouc will go down a road of misery with her. In a newly added plot to the movie, it is revealed that she had Poirot look into the Otterbournes and the relationship to find out if anything was amiss. He concludes they are a good match. However, tragedy strikes later when Bouc is killed during his interview with Poirot, who is about to reveal Jacqueline de Bellefort (Emma Mackey) as one of the killers.
As Death on the Nile marks Bouc's final appearance in the movies, his mark on Poirot's life as a friend was profound. In comparison to the Agatha Christie books, Bouc was far more fleshed out in Kenneth Branagh's version, even if his character served as a direct replacement to one in the book. Audiences can only hope that his memory is now put to rest after his detective friend solved the case in the end.