Flares include grain assemblies comprising a combustible grain and a reactive foil positioned at least proximate to the grain and configured to ignite combustion of the grain upon ignition of the reactive foil. The reactive foil may include alternating layers of reactive materials. Methods of fabricating flares include at least partially covering an exterior surface of a combustible grain with a reactive foil to form a grain assembly, and inserting the grain assembly at least partially into a casing. The reactive foil may include alternating layers of reactive materials that are configured to react with one another in an exothermic chemical reaction upon ignition. Furthermore, methods of igniting a flare grain include initiating an exothermic chemical reaction between alternating layers of reactive materials in a reactive foil located proximate to the flare grain.