The man whose funeral Bloom attends in Hades, Patrick (Paddy) Dignam, was not based on any actual individual. Joyce made this fictional character emblematic of two corporeal conditions: the universal human liability to becoming suddenly extinct, and the pervasive Dublin flaw of drinking too much alcohol. Both are implicit in the book's first mention of Dignam in Calypso: "Stop and say a word: about the funeral perhaps. Sad thing about poor Dignam, Mr O'Rourke."
Why should Bloom, who drinks very little, assume that Larry O'Rourke, who owns the pub at the corner of Eccles and Dorset, knows Paddy Dignam? Probably because he passes through the pub from time to time and knows that Dignam was a regular customer.
In Hades it becomes apparent that Dignam's drinking has cost him a good job, like many other Dubliners in Joyce's fictions. He used to work for John Henry Menton, a solicitor. Menton attends the funeral, and Ned Lambert mentions that he has contributed a pound to the collection that is being taken up for Dignam's wife and children:
— I'll engage he did, Mr Dedalus said. I often told poor Paddy he ought to mind that job. John Henry is not the worst in the world.
— How did he lose it? Ned Lambert asked. Liquor, what?
— Many a good man's fault, Mr Dedalus said with a sigh.
Simon Dedalus, of course, counts himself among those good men, and has himself lost good jobs along his trail of alcoholic ruin. In Penelope Molly thinks approvingly of her husband's refusal to waste their family money in bars the way Dignam has: "he has sense enough not to squander every penny piece he earns down their gullets and looks after his wife and family goodfornothings poor Paddy Dignam all the same Im sorry in a way for him what are his wife and 5 children going to do unless he was insured comical little teetotum always stuck up in some pub corner and her or her son waiting Bill Bailey wont you please come home."
Unsurprisingly given the medical science of the time, Dignam's cause of death is not clearly specified in the novel. Oxen of the Sun and Ithaca identify it as "apoplexy," an often imprecise medical term which from medieval times until the 20th century could be used for any incident in which the victim suddenly lost consciousness and died. A heart attack or stroke (both of which can be brought on by heavy drinking, via raised blood pressure) seems mostly likely, but any such speculation would be extra-literary. Starting in the late 19th century, the term began to acquire its present meaning of internal hemorrhaging. Whether or not Joyce was aware of this new, more precise meaning also seems uncertain.