The Valkyrie's Shadow by Tiana Warner

Being both a valkyrie and a princess isnt turning out quite the way Sigrid imagined. The other valkyries still treat her like a stable hand. Her relationship with Mariam is less -oelong-distance- and more -oeworlds apart.- And lately, shes been wondering if Sleipnir, her new horse, isnt making her a little bit-¦well, evil .

But Sigrids first official valkyrie mission sends ripples through the Nine Worlds. Shes attracted the wrath of not only the Night Elves but their sinister king, who wants nothing more than to bring darkness down on everyone. Worse yet, Loki might just be interfering with the balance of light and dark-¦

When war threatens the shores of Vanaheim and her friends are in danger of being exiled, Sigrid makes a deal with the new queen. She will ride Sleipnir against their enemies and use his might to defeat them, even as he pulls her closer to that line between good and evil.

What she becomes will either save everyone-¦or unleash disaster upon them all.

The Sigrid and The Valkyries series is best enjoyed in order.
Reading Order:
Book #1 The Valkyries Daughter
Book #2 The Valkyries Shadow