Crazy guesses about the fanfiction Terran Ingenuity.
Kerrigan will play the role of Cerberus.
Whatever drove the Terrans from Koprulu also knocked Kerrigan from her place at the head of the Swarm. As the fic begins, her splinter Brood will make its way to Shanxi (or nearby). She'll lay low for a while, using semi-infested Terrans as agents. She'll also resurrect Shepard in a similar fashion.