Rogue looked up at him silently before slowly nodding her head. "The longer Ah hold on to the person, the more ah take and it becomes permanent", she explained softly, "Power transfer can be permanent as well as memory in some cases. It depends on how long ah come in contact with the person". Ms. Marvel was a perfect example of this aspect of her ability, of course Ms. Marvel was also not fully human, which Xavier had explained could contribute to the last effects she had upon Rogue.
"Ah can't fully pick or chose which memories Ah take at the time of touch. However, even after the psyche of that person returns to their body, Ah retrain some part of them, an echo, in my conscious", she continued took a deep breath and started once more. " Ah take their abilities, but Ah can pick and chose how to use them, though the process itself is usually temporary".
She swallowed and tackled the last half of her ability with a quiet voice. "Ah can chose to kill a person by taking too much of their energy and holding on too long".