So we all know that Darkness of one's Heart grows through experiencing intense negative emotions, doing evil deeds, or using the Darkness if one knows how until they eventually go insane or become a Heartless. But is it possible to diminish the Darkness in one's Heart? I know that it's impossible to completely get rid of the Darkness but can it's effects be reversed? Let's use Terra and Riku as an example: the Darkness in their Hearts continued to grow as they used it but they became strong enough to not be corrupted by it (not counting possession by Xehanort) but it's never stated the Darkness goes down, it just stays there. Meanwhile, those who have come back from being Heartless seem to have the Darkness of their Hearts reset to what it was before it started growing. Is coming back from being a Heartless the only method of diminishing the Darkness in one's Heart or are there other ways that are not mentioned in game, only in those damn books and interviews that are never published outside of Japan?

i would assume it's possible to lessen the darkness in your heart. since you can increase it through your own thoughts and actions, it would make sense that you'd be able to decrease it by the same means. maybe it just comes down to having the strength to overcome it if you let it get too far.

 

A little darkness in your heart might not be that big of an issue to deal with but for Terra and Riku who were really close it, they had a harder time controlling it. 

I'm not sure if they've been that explicit over whether or not you get "more darkness" into your heart or if the same amount of darkness is always there and simply gets stronger over time. In either case though, I don't think those semantics are as important, what matters in the end is how much influence or control it has over you. Darkness, as we've seen, isn't all evil, but it's been exploited by evildoers for many years and the Heartless may also possibly be a byproduct of the disbalance. Whether the Heartless themselves are evil or not kind of depends on your point of view, on the one hand they want to kill everyone and keep growing and infesting the worlds, on the other hand though they seem to act as any other species of animal or insect naturally would, not even aware of whatever consequences their actions bring. In any event. Despite it's tendency to be used by the wrong people for the wrong reasons though, it would seem that it still exhibits some traits independently that would still seem more sinister or dangerous compared to light. It's natural reliance on anger, sorrow, jealousy, and other negative emotions kind of makes it seem like a negative force already, and those who lean towards it more tend to have less rationality or compassion towards others.

 

However, it might still be less of a matter of becoming more "evil" and becoming more negative and less balanced. It seems that darkness also tends to be used as an easy shortcut for power, as those with darkness tend to be a lot stronger than the average person or even those on the side of light. But maybe this gives some insight as to how the balance of light and dark works. Despite the fact that we need both to exist, everyone in the Realm of Light seems to naturally lean towards and rely upon light much more than darkness, and it makes sense, if you're in such a realm then naturally you're going to be more preferential to what's in abundance. But then perhaps the trade-off is in how powerful darkness is even in small amounts, that way you could still be a balanced person by being more of a light-user because whatever darkness you have in you is already strong enough to balance you out. This would also explain why darkness seems to be so much more powerful when tapped into.

 

I'm not as sure about whether amounts of darkness are gained or lost over time due to circumstances, I honestly don't remember how in-depth the series got with that, but the impression I got was that varying people had differing amounts of control and influence over darkness and vice versa. So maybe it's more similar to a substance, how much is in you at any one time doesn't affect you so much as it's lasting affect on you psychologically always remains, if you become addicted to darkness then you are in trouble. Whether the amount of darkness any one person has in them at any one time affects their disposition or not, I think we can at least agree that the strength of the influence of that darkness is what is responsible for the more negative traits of those who are under it's sway. That's why certain people like Riku are exceptional in that he still uses the power of darkness but to a much greater degree of control, it no longer influences him like it used to, he is able to be who he fully and truly is while using all of his power to his disposal. He's in control of his own strength, and not the other way around.