Moon Child - A Legend of Korra Fanfiction

One year after the defeat of Kuvira, Mako is back on the Republic City police force. When a sting meant to take down a remaining faction of the Triple Threat Triads goes awry, Mako makes an arrest that turns everything upside down.
At first, Mako and everyone on the force dismiss everything the dirty, weird-looking girl says as the ramblings of a homeless lunatic. But when a giant, powerful spirit attacks Republic City, their only hope to stop it rests with the girl everyone thought was crazy. Soon, they find that the giant spirit was only the beginning, and the girl named Ula may be their only chance to stop a war that's been brewing for decades.