The labor lasted through the night and into the grey edge of morning, timed almost exactly, Jasmine would later think, with the battle raging beyond the fortress walls — as though the twins had chosen to arrive in perfect, terrible synchrony with the war their existence had caused.

There were moments, deep in the worst of it, when the pain blurred everything else into a single roaring wall of sensation, and Jasmine found herself gripping Xavier's hand hard enough to bruise, murmuring half-formed promises to children who couldn't yet hear her — that she would keep them safe, that she would build them a world with fewer storms than the...