Thread:Kirito Rose/@comment-25110963-20160519052819/@comment-26397825-20160523124827

Actually, Life's Blood (orlifeblood) is a phrase. From two official dictionaries and one urban dictionary, the meanings are as such:

life's blood lifeblood life blood
 * The reason for someone to exist. The absolute love and obsession of a person's life.
 * blood regarded as the seat of vitality
 * a vital or life-giving force or component 
 * Blood regarded as essential for life.
 * An indispensable or vital part: Capable workers are the lifeblood of the business.

So while the vital bodily part is indeed a common meaning of it, it also has another meaning that is a bit more poetic.