I believe it is a quick Transmigration novel, the apocalypse arc is the only one i remember. The MC is undercover as a boy named Cecile but is actually named Cecilia i think. She exposes her true gender when the apocalypse is announced and ML looks at her with internal dialogue about how he thought MC was a boy and not a girl. MC has lava powers and ML has ice powers, in one of the scenes Cecilia makes a lava path from a window to somewhere else and ML makes the same thing but with ice, telling people to follow him, one of the people's internal dialogue says something about how he thought MC would have the ice powers and ML would have lava powers, not the opposite. Found on wattpad i think.