Loki's up to all his usual tricks in this story:
We're not exactly sure why Loki encourages the gods to agree to the stone-mason's deal, but given his love for stirring up trouble, we're guessing he knows exactly who the mysterious stranger is, and just how close the gods will come to losing Freyja, the sun, and the moon, before all is said and done.
Of course, once the gods are in a tight spot, Loki gets to play the "hero" by doing other Loki-esque things: shape-shifting, gender-bending, and giving birth to a mutant "child." The gods are lucky that, at least this time, Loki's offspring turns out to be just the horse Odin needs, rather than an apocalypse-inducing monster.
Want to learn more about Loki? Check out our Loki Files.