Lilia Greyrat trained at a Southern Region swordsmanship dojo within the Asura Kingdom under her parents, Augusta and Flute, masters of the Water God Style. She studied alongside classmate Paul Greyrat. During their youth, Paul sexually assaulted her while she slept, resulting in the loss of her virginity. She later reflected this event might be preferable to potential encounters with nobles in her future service. Paul subsequently departed the dojo.

Lilia secured a position as a guard-maid for the Asura Kingdom's royal palace, balancing domestic duties with royal protection. When an assassin targeted Princess Ariel Anemoi Asura, Lilia intercepted the attack but sustained a poisoned blade wound to her leg. The specialized royal-targeting poison inflicted permanent damage, leaving her unable to run or exert full strength despite surviving. Dismissed from service due to her disability, she concluded the kingdom viewed her as expendable. Seeking anonymity, she journeyed to the remote Fedoa region.

In Fedoa, Lilia responded to Paul Greyrat's advertisement seeking a maid experienced in childcare and midwifery for his pregnant wife, Zenith. Paul hired her despite their shared history, offering unexpectedly high wages. She assisted Zenith during Rudeus Greyrat's birth but developed immediate distrust of the infant, perceiving his expressions and behavior as "perverted." She actively avoided him and discovered, but kept secret, his hidden stash of Roxy Migurdia's undergarments.

Years later, Lilia became pregnant by Paul, amidst Zenith's second pregnancy. She confessed to initiating their affair and offered to leave the household, accepting the risk of death during winter travel. Rudeus intervened, falsely claiming Paul had coerced her, securing her acceptance into the family as Paul's second wife. This act forged deep loyalty in Lilia, who vowed lifelong service to Rudeus and dedicated her daughter Aisha to become his future maid. Aisha was born hours after Zenith delivered Norn.

During the Teleport Incident, Lilia and Aisha materialized within the Shirone Kingdom's royal palace. Authorities imprisoned them as suspected spies. Despite invoking Roxy Migurdia and Paul Greyrat's names to lessen charges, Prince Pax Shirone later confined them as bait for Roxy. During imprisonment, Lilia rigorously trained Aisha in maid duties, academics, and social etiquette, explicitly preparing her to serve Rudeus. She instructed Aisha to leverage her cuteness to manipulate others, including guards. When Rudeus was captured, Lilia attempted a rescue, but her leg impairment caused failure. After Rudeus secured their freedom, she presented him with his treasured box and requested Aisha become his maid, reluctantly accepting his refusal.

Lilia attained Intermediate rank in Water God Style swordsmanship but lacked the skill to instruct others. Her leg injury permanently crippled her combat effectiveness. Physically, she possessed reddish-brown hair typically tied in a half-bun, violet eyes, a voluptuous figure with large breasts, and wore oval glasses and a hairband as part of her maid outfit. Personality-wise, her guard-maid training instilled emotional restraint, though she became more expressive after marriage. She held superstitious beliefs, initially interpreting Rudeus's behavior as demonic possession. Her loyalty to Rudeus became absolute after he saved her from exile, driving an unwavering commitment to repay her perceived debt.