My Kingdom for a Snake (слэш)

In all the Nine Realms, all intelligent beings receive a spirit animal. It does not appear as a babe is born. Babies are clean slates, showing nothing except potential. No, a spirit animal is called at a very specific moment in time. It may not be a pivotal moment in that person’s life; it may not even be a particularly big moment altogether, but each person has a moment like this. One that sets the shape for who they will be.
Both Loki Odinson and Tony Stark are thrilled to receive their spirit animals. The rest of the worlds have their own opinions that Loki and Tony handle in very different ways. While Loki invades Earth, they find themselves on opposite sides, right up until they find out that they have more in common than they ever could have guessed!