How does Yeremei the porter relate to the major character/themes in the story, "On Account of a Hat?"
Yeremei, the porter, works at the train station at the Zlodievka station. Sholom Shachnah asks Yeremei to wake him up if he should fall asleep. Sholom is afraid he will sleep and miss his train. Sholom falls asleep and dreams that he is riding home for Passover on a slow wagon driven by Ivan, a "thievish peasant." Sholom commands him to speed up; eventually he does and Sholom loses his hat. Ivan comes to a halt and this is where the dream segues into Sholom waking up to Yeremei's words at the train station.
This is a comical story about an absent-minded man, but on a more serious note, it shows a cultural contrast between Sholom's self-conception as a Jew and the external conception of Jews by the Gentile population. When Sholom mistakenly takes the Gentile official's hat, he is treated like royalty. When he realizes his mistake, he believes he is still dreaming on the bench at the station; he returns to wake himself up and consequently misses his train.
Sholom realizes that he had been treated so well only because he was wearing the Gentile official's hat. In a sense, he felt more comfortable or familiar riding in third class. This shows the limited self-conception he had of himself as a Jew in Gentile company. This says something about the way Jews were treated by Gentiles in this pre-WWII Eastern Europe. Yeremei is a side character in this story but the narrator does make it a point to note that he is a Gentile as well. In the end, Sholom blames Yeremei for not waking him up. He assumes that Yeremei, a Gentile, chose to wake up his fellow Gentile officer instead of waking him (Sholom). Although it was Sholom's absentminded behavior that made him miss the train, he blames it on the Gentile, assuming that Yeremei had it in for him from the start.
Twenty times I tell him to wake me, and I even give him a tip, and what does he do, that dumb ox, may he catch cholera in the face, but wake the official instead!
This shows Sholom's "rattlebrain" tendency but it also shows how Sholom, a Jew, viewed Gentiles as antagonists, a subtle indication showing Sholom's awareness (albeit misguided in this case) of antisemitism.