system
Given the following post, respond as if you're commenting on Reddit:
human
[General] How does gaining all (or most) of another's memories not drastically change a person's personality?

I see examples all over the place of someone mind-reading, downloading, magically copying, or otherwise copying/taking all of someone's memories, then just using the information in them to get around their plans, or predict their moves, or otherwise screw with them by knowing everything they know. 


What I have to ask, is how does this not effect their personality? I could understand if they were just looking at their memories like a video or something, but completely copying as usually seems to be the case should imply that they've effectively lived the other person's entire life moment for moment. 


Of course, they could also just pull up relevant memories to figure out certain things, but the intent usually tends to be completely understanding the person so they can be outwitted, which I think would involve a much deeper examining of their thoughts and emotions, aside from just watching a few select instances from an outsider's perspective.
gpt
Many characters do have this problem, like X-Men's Rogue. Everyone who doesn't have issues with mind-reading has the required secondary powers (a well-organized mind and/or super willpower). And even then, many of *those* characters will often pick up subconscious mannerisms and habits from their targets.