This is the kind of question I like to put on a “mental list” of questions to ask in eternity since they are all but impossible to answer in the here and now. At most, we can say that it is possible that the “fighting in heaven” is a metaphorical picture, possibly just as much as are golden streets, halos and harps, and pearly gates. Ultimately, St. Michael and the good angels triumphed by their choice to serve God, while Satan and the devils were defeated by their choice to reject God.
