The modification, loss, and gaining of memories by a character that is of plot significance, through means that are not natural. For example: falling down stairs and receiving brain trauma could be considered natural in this context, whereas falling down stairs into another dimension and passing/gaining inter-dimensional memories would not. Memories do not necessarily need to be genuine, the only requirement apart from the natural cause is that after the memory modification event (be it via reality warps, a machine, magic powers or otherwise) the "new" set of memories are different from the "old" set of memories, even if only slight. May sometimes overlap with amnesia depending on the circumstances.