When describing Lenehan’s character early in the story, the narrator uses two metaphors, as seen in the following passage:
Most people considered Lenehan a leech but, in spite of this reputation, his adroitness and eloquence had always prevented his friends from forming any general policy against him. He had a brave manner of coming up to a party of them in a bar and of holding himself nimbly at the borders of the company until he was included in a round. He was a sporting vagrant armed with a vast stock of stories, limericks and riddles.
The first metaphor here—“Most people considered Lenehan a leech”—is quite straightforward. The people in Lenehan’s social circles see him as a leech—or blood-sucking animal—because he doesn’t pay for his own drinks but waits “until he [is] included in a round.” In this way, he is financially “leeching” off of those around him. Beneath this kind of leeching is the reality that Lenehan is struggling financially (in part due to Ireland's unstable economy) and doesn’t know how to talk about it.
The second metaphor here is a bit more complex. In referring to Lenehan as “a sporting vagrant armed with a vast stock of stories, limericks and riddles,” the narrator is comparing Lenehan to a sort of military figure “armed with a vast stock.” Rather than literal weapons, however, he is stocked with “stories, limericks and riddles.” With this metaphor, James is highlighting how Lenehan’s social skills are one of the reasons he is able to survive—because he is funny and sociable, the people around him will pay for his food and drinks. The narrator’s militaristic language helps readers to understand that this is a skillset Lenehan is leveraging in order to stay alive. Because of his financial situation, this is more than just fun and games for him.