So in the Binding of Isaac, the characters use their tears as projectiles; Lilith, however, uses a familiar that she starts with to fire her tears instead, as she is unable to directly. To visually show Lilith inability to shoot, Edmund made he start with a blindfold. There could be more backstory to "Lilith" outside of Edmund's game, but I have no clue. Might even be a reason for the blood, even though it quite possible he added it for extra "reassurance" that we know only her babies can fire for her.She also starts with an item called "Box of Friends", which when used, double all the familiars she has for the current room, hence the peering of familiars and Lilith.I guess this could explain her better.The story of Lilith outside of Edmund's game? I have no real idea and no intention to know.