- She is ambitious and goal-oriented.
- She fervently champions causes.
- Some of these causes are not understood or accepted by those they are meant to help (eg SPEW).
- Her morality is the only morality she cares about (see SPEW again).
- She has proved herself willing and capable to go to extremes/be ruthless when upset, for her beliefs, or for those she loves.
- She is the brightest witch of her age (power corrupts).
- She was taught by the best friend of the previous Dark Lord and teacher to the most recent Dark Lord to lie and use special tools to get unfair advantages (eg the time turner).
- As a war hero, people will be more inclined to follow her.
- She avenges perceived slights physically and with magic (eg punching Malfoy and siccing the birds on Ron).
- She makes decisions without consulting those it affects (eg wiping her parents' memories).
- She is willing to break rules when they conflict with what she desires (basically, the entire series is predicated on the three of them doing this).
None of this means that she has to be the next Dark Lord/Lady, but I can't think of a better candidate from the books. I can easily see a situation where she comes to believe something must be done and then forces the rest of the wizarding world to bend to her will by any means necessary to make it happen.
Do you agree with Shog that Hermione has the potential to be a Dark Lady?
When I think about Hermione bending the wizarding world to her will by "any means necessary," I envision her as a Dark Administrator, a well-meaning bureaucrat who might, say, foist a marriage law, or some other evil, upon the populace.
What do you think a wizarding world with Dark!Hermione in charge of it would be like? What would be her raison d'être? Conversely, if you just can't see Hermione as evil, well-intentioned or otherwise, why don't you? What about her makes her destined to remain upon the side of the Light?