“A Little Hero” (“Маленький герой”), by Fyodor Dostoyevsky (originally under the pseudonym “М-ий”)
According to the Russian Wikipedia, written in prison and first published in 1857 in the eighth issue of the magazine Отечественные записки/Otechestvennye Zapiski (Notes of the Fatherland); collected in White Nights and Other Stories, translated by Constance Garnett (on Gutenberg.org); also online here
14,930 words in English
Have I mentioned I’m a sucker for a well-written child character? And for Dostoyevsky’s children especially? I love the cruelty of the coquette who teases him, the way he demands respect and gets it, his childishness even as he edges near adolescence, and above all, the ending.
Any story about a child or adolescent is liable to read as a coming-of-age story, because like any main character, the child/adolescent must change in some way. (Though there are exceptions, like “Voices Lost in Snow.”) “A Little Hero,” however, seems to portray a genuine coming of age, as its main character learns to deal with the first blushes of sexuality, to assert himself, and to take action for others’ sakes.
Like most of my favorite first-person stories of children, this one is clearly narrated by the adult, with complete sympathy for his childhood self.
What a thing to have written in prison! What a thing to have written with a death sentence hanging over your head!