Katelyn was born to a family of four, her parents being called Sarah and Roderick Hearthdale. She had one brother named Theodore and a sister named Eliza. Their family ran a small inn within the town of Northdale, a nice rest stop between Lordaeron and the road to Quel'thalas. Katelyn spent much of her youth assisting her mother with the inn alongside her sister, while her father and brother served in the military. Her brother was killed in the second war, her father fighting on during it. Her father carried a mace, dubbed "Orc Crusher" by himself for crushing the skull of the orc who slew his son. As Katelyn grew older, she trained to become a priestess.
As she grew older, she learned to fight, this being when her father returned from the war. Though soon after, the fall of Lordaeron would occur as the scourge ravaged across Lordaeron. Her father and mother fell as Northdale was sacked by the scourge, their fate unknown to Katelyn and her sister as they fled Lordaeron and ventured south with the refugees. Although, during this Katelyn and her sister split up, Eliza venturing with a group west and eventually to the Scarlet Monastry while Katelyn fled to Stormwind with other refugees. During her later years, Katelyn trained to become a Paladin in Northshire abbey, studying under the mentorship of a paladin named Lorthentus Theodore. As time passed, she succeeded in her trials and become a fully fledged paladin, being knighted aswell. She continued to serve the Alliance military in various campaigns, fighting the Horde on many occasions.