Of Mimir's well — in the Norse telling, the spring of memory and wisdom that had to be paid for. In this house, the vault of an excavated life.
Old Norse Mimir, a being associated with wisdom and memory, keeper of a well whose water granted knowledge to whoever paid its price; the possessive form used for whatever belongs to that well.
The vault where an excavated life is kept — named for a well that gave up wisdom only at a price, which this house's own memory still asks in its own way.