In what way is "The Rattrap" by Selma Lagerlof a Christmas story?
"The Rattrap" is a Christmas by virtue of setting and thematic concern. The story opens with the rat trap seller wandering in a forest "late in December" in which "[d]arkness was already descending." He finds his way to the Ramsjö Ironworks where he can warm himself at the forge fire where the ironmaster and his blacksmiths are still gathered "[d]uring one of the long dark evenings just before Christmas." This setting clearly establishes this story as a Christmas story.
The predominant theme of the story is that of redemption through the gift of charity and peace. The rat trap seller is mistaken for an old friend of the ironmaster and taken home for Christmas festivities. There, even though his true identity of vagabond and petty thief is disclosed, he is given peaceful rest, plenteous good food, and the gift of a suit of clothes:
he went around to each one ... [when he] came to the young girl she gave him to understand that it was her father’s intention that the suit which he wore was to be a Christmas present—-he did not have to return it; and if he wanted to spend next Christmas Eve in a place where he could rest in peace, ... he would be welcomed back again.
In response to being treated as an elevated person, he delves inward and acts like an elevated person. We aren't told what he continues to do, but we are told that he now thanks the ironmaster's daughter for her courteousness and generosity and gives her the money to return to the crofter, a tenant farmer, from whom he stole it after receiving the crofter's hospitality of supper, conversation, a bed, and breakfast. This theme and these redemptive acts surely mark this as a Christmas story.