Very little is known of Lillith pre-Incident #304. It is known that she worked for the major pharmaceutical company known as [Redacted] which, subsequent to the revelation of their involvement with Sceptre Facility #[Redacted], lost all business and became bankrupt.
Lillith proved useful to Eve during Incident #304 to her tenacity and moral support. Whilst evidence suggests that Lillith came face to face with [Redacted] and won, her physical and mental tenacity would've been the strongest factor in this conflict and not her physical and mental strength. She did, however, have an encounter with Ravenna Marcello to which caused her to break down emotionally and mentally, it is unknown what she used as a vice to keep going after the encounter. During Incident #304 Lillith also chanced upon a sample of Vitalis Mortia, that Eve had been using to manufacture Everun, which she ate. No testing has been previously adminstered on the affects of ingesting the mushrooms. The only testing run on Vitalis Mortia were to isolate the chemicals Everun and Everide. The mushroom itself was originally thought to be to weak to be used in any form of experiment.
Upon escaping Sceptre Facility #[Redacted] Lillith was caught by Sceptre Officials, an attempt to interrogate her failed when she fell to the floor convulsing and spitting blood. Upon medical examination of her corpse, a strange fungal infection was found in her stomach that had been excreting toxins directly into her bloodstream. Most likely caused by the dominant presence Everide in the mushroom. It isn't known why the presence of Everun didn't have an effect, the most probable theory is that the replacing of certain proteins in the brain cells by Everide prevented the reaction that Everun requires to take affect.
Lillith's relationship with Eve, was little more than a weak friendship formed under the pressure of being trapped miles underground.
Her relationship with Joshua was little more than an aquaintance. They barely spoke, and the words they did speak to eachother were short and blunt. The reason for this hesitation to become aquaintenances is still unknown.
There is no evidence to suggest Lillith even knew of her existance until the encounter during Incident #304.