But then, it is pretty much the premise of this fic that Harry doesn’t obey “natural” ten-year old cognitive constraints because he is a prodigy by birth (with top-rate education that has allowed him to draw on his full mental potential). That premise accepted, there is nothing implausible about his dark side simply focusing his mental capabilities and allowing him to reach new levels of performance (at the cost of limiting processing in other areas such as empathy).
But then, it is pretty much the premise of this fic that Harry doesn’t obey “natural” ten-year old cognitive constraints because he is a prodigy by birth (with top-rate education that has allowed him to draw on his full mental potential). That premise accepted, there is nothing implausible about his dark side simply focusing his mental capabilities and allowing him to reach new levels of performance (at the cost of limiting processing in other areas such as empathy).