Dragon Ascendant by Elana A. Mugdan

A dragon who can't wield magic.

A human who hates dragons.

A secret so powerful it could destroy both their races.

Isidra and Syl are different as different can be. Isidra yearns to become one of the Andarae, a global peacekeeping force of mortals and dragons. Syl has a deep grudge against the Andarae because they betrayed her family.

When a magical accident binds Isidra and Syl together, they're forced to team up as a dragon-rider pair and train with the Andarae. That would be bad enough, since the two of them can't stand each other. Then bodies drained of blood start turning up, and it becomes clear that someone's hellbent on destroying the Andarae from within.

With the future of both their races at stake, Isidra and Syl must put aside their differences to solve the murders. But that puts a target on their backs, which means the next bloodless corpses might be them. They'll have to stay one step ahead on this magical murder mystery...

Because if they can't learn to work together, they'll die together.