Sleipnir
Steve leapt up from his seat as the eight-legged horse ran past the window. "Holy cow!" he shouted. "Did you see that?"
"Hmm?" Sif looked up from the sheaf of battle plans she was studying and peered out through the glass. "Do you mean Sleipnir? That is the son of Loki."
Steve's face turned bright red. "Loki's son, did you say?" His voice turned into a squawk.
"Oh, yes. Well, not by Natasha, of course, but when he was young, he had to distract a stallion by the name of Svaðilfari in order to save Valhalla and Freya's virtue, not to mention the sun and the moon – well, it is a long tale. The upshot was that he turned himself into a mare, was caught by the stallion, and there is the result running outside the window."
"Huh." Steve put one hand on his chin. "I can't say I've ever heard anything like that before, ma'am."
Sif snorted. "Sleipnir is nothing compared to Jorgmunsdir."
He turned quickly away from the window and put out a hand for the battle plans. "Just give me some work to do. I don't even want to know."