It was destiny. Starclan knew that Scourge would take them all at once and they wanted Tigerstar to know what true fear was like. But Tigerstar was also a strong warrior that every kit looked up to and wanted to be when they became warriors. They probably gave him his lives in honor of the strong and honorable warrior that he was before he became power hungry.
He was already quite power-hungry when he joined ShadowClan.—|| Grudgeholderr ||— 10:41, February 9, 2018 (UTC)