Memories

The silver ball hovered in the air, wisps flying as it soared up the stairs and railing and into the parlor. No sooner had it been volleyed back, landing again in Death's hand. "Disgusting." Life's horrified expression needed no explicit visual confirmation.
"These are your creations," Death said pointedly, ascending the staircase. "See in what they choose to engage." With another push upward, the ball of energy flew back toward Life.
"I would prefer otherwise." Life deferred it with the wave of a hand; it turned away from both of them, sailing down a hall. "I can only imagine that They were blind to that fervor, when deciding to mold us after them."
Death shuddered, sitting promptly across from Life. "To suffer with their memories is a curse enough on my existence."

Manifestation

Within the souls of sentient creatures, the memories are etched into permanent existence, allowing for the soul to carry the personality, thoughts, and emotions of the person after leaving the body. Generally manifesting as the death energy, as the 'spent' energy of the soul, it may be removed, transferred, or read by any being which acquires the energy. (Less often, it may involve etchings onto life energy.) With the soul as the 'library of memories', it is possible to remove memories by removing the specific energy, or share them in similar conduct. While this is common practice between Life and Death, it is mostly unheard of otherwise, and is thus not discussed with other forms of magic. However, human memories may be removed or modified by them, and the viewing of others' memories using this is involved in certain forms of Projective Magic .
Memories are rarely larger than the flame of a candle; collections of them may grow larger, but as they cannot homogenize into a single ball of energy, it is a bit equivalent to trying to form a ball out of several broken strands of old spaghetti.
When viewed, they invoke any physical sensations or emotions alongside the memory, as if the viewer were suddenly the original person in that second. This may be deconstructed and modified over time, as the memory is relived by the original person and rebuilt; however, an outside viewer will always see the most clearly constructed version available. That said, memories not originally formed cannot be 'unlocked'; only conscious memories may be viewed or modified. (Memories may be made 'unconscious' or 'locked', however.)