It's been a hot minute since I made a thread here but I wanted to express what I think would make the most sense for "the box" as well as express a few other theories I have after viewing the finale of Union X.
First off, what is the box for? Well, given that there's been all of this discussion surrounding the 7 deadly sins (plus the 6 lesser sins that were mentioned by MoM), it seems very clear, especially now, that this is a sort of Pandora's box. Not in the literal sense, as we've previously seen the actual Pandora's box in Olympus in KH3 (which funnily enough has very little significance to the characters of Kingdom Hearts). The black box is a Kingdom Hearts version of Pandora's box and is rather a box of darkness. I mean, even at face value you can tell that the box has something mischievous going on with it. It has the same color scheme as Vanitas and his keyblade who has now been all but proven to be one of the 13 darknesses (which he seems to be the sin of vanity, which I think in terms of the sins in KH will likely be one of the 6 lesser sins). What I'm fully expecting from the box is that it will be a way to capture these darknesses of sins once they fall in battle. Or perhaps it is the "Kingdom Hearts" of sorts for darknesses. Hearts of light return back to Kingdom Hearts upon death. Perhaps these essences of darkness return to the box when they fall.
This would explain why Luxu must take the box into the future to a time when all of the darknesses have been given forms. That way they can finally be fought and returned to the box. In this future time period, it is shown that disney villains such as Maleficent have an interest in the box. Disney villains (at least the older ones) usually are characterized as being "pure evil." They don't usually have much of a backstory other than being innately evil and have a hatred of the hero character. This would make a whole lot of sense in Maleficient's case as she knows of the box and what it might contain. Having access to the evil that the box holds/will hold could lead to great power and control over the darkness or just complete chaos, things that a villain of pure evil may desire.
To me it is very clear that the box is meant to hold these 13 darknesses. What is currently *unclear*, however, is how many darknesses have fallen. It has been shown that, at the very least, 6 individuals are currently holding these darknesses of sin, those being the foretellers minus Ava (who is currently missing, may be deceased, maybe not, who knows), as well as Luxu and the Master of Masters. Vanitas was defeated and so if we assume that he was one of the lesser sins, he is likely currently captured in the box or is formless outside of the box depending on if Vanitas "really" died in KH3. Aside from that, we're kind of left in the dark as to where the remaining darknesses are. We know at least 4 of them have been trapped inside a portal between worlds (but will likely escape somehow in the future) and then there's one more unaccounted for.
As for the dialogue from Back Cover between the Master and Luxu regarding the box... When the Master whispers to Luxu in that scene, I imagine he said something along the lines of, "this box holds/will hold essences of pure darkness and sin." I think to something like that Luxu's shocked reaction of "But why?" makes a lot of sense. At that point it would make sense for Luxu to be concerned about the Master keeping a box filled with darkness and sin. What makes this all even more interesting is how the Master responds to Luxu very ominously when he says "You'll see..." I'm getting a little ahead of myself, but to even further push this theory past the point of any hard evidence, I'm thinking that perhaps once all of the darknesses are returned to the box they'll form into a weapon similar to the X-blade which would explain the "X Super" written on the top of the box. Again though, that's really pushing it but that's my current head canon and perhaps the Master's true goals aren't to defeat darkness but rather to wield it as a weapon.
And finally, back to the four darknesses who have been trapped between worlds in the portal with the player character... I think that the player character might pull off something similar to what Sora did to help Ventus complete his heart so that he could wake up in BBS on destiny islands. Perhaps Xehanort was born without a heart or with a weakened one, hence the anagram "No Heart" that people toss around. The mother didn't know what to do and so she gave the child up in the hopes that they would awaken on Destiny Islands (somewhere that seems to be frequently associated with awakening of characters). The player heart BECAME Xehanort's heart at Destiny Islands and allowed him to truly come to life. The player's heart has been shown to be fairly resistant to the darkness, after all, and perhaps Xehanort would use that aspect of the Player's heart to be able to control the darkness without it inhabiting his heart.
So yeah, those are just my thoughts and theories on the box + a few other things. Let me know what you think, especially the theory on the box because to me this hits the nail right on the head!
First off, what is the box for? Well, given that there's been all of this discussion surrounding the 7 deadly sins (plus the 6 lesser sins that were mentioned by MoM), it seems very clear, especially now, that this is a sort of Pandora's box. Not in the literal sense, as we've previously seen the actual Pandora's box in Olympus in KH3 (which funnily enough has very little significance to the characters of Kingdom Hearts). The black box is a Kingdom Hearts version of Pandora's box and is rather a box of darkness. I mean, even at face value you can tell that the box has something mischievous going on with it. It has the same color scheme as Vanitas and his keyblade who has now been all but proven to be one of the 13 darknesses (which he seems to be the sin of vanity, which I think in terms of the sins in KH will likely be one of the 6 lesser sins). What I'm fully expecting from the box is that it will be a way to capture these darknesses of sins once they fall in battle. Or perhaps it is the "Kingdom Hearts" of sorts for darknesses. Hearts of light return back to Kingdom Hearts upon death. Perhaps these essences of darkness return to the box when they fall.
This would explain why Luxu must take the box into the future to a time when all of the darknesses have been given forms. That way they can finally be fought and returned to the box. In this future time period, it is shown that disney villains such as Maleficent have an interest in the box. Disney villains (at least the older ones) usually are characterized as being "pure evil." They don't usually have much of a backstory other than being innately evil and have a hatred of the hero character. This would make a whole lot of sense in Maleficient's case as she knows of the box and what it might contain. Having access to the evil that the box holds/will hold could lead to great power and control over the darkness or just complete chaos, things that a villain of pure evil may desire.
To me it is very clear that the box is meant to hold these 13 darknesses. What is currently *unclear*, however, is how many darknesses have fallen. It has been shown that, at the very least, 6 individuals are currently holding these darknesses of sin, those being the foretellers minus Ava (who is currently missing, may be deceased, maybe not, who knows), as well as Luxu and the Master of Masters. Vanitas was defeated and so if we assume that he was one of the lesser sins, he is likely currently captured in the box or is formless outside of the box depending on if Vanitas "really" died in KH3. Aside from that, we're kind of left in the dark as to where the remaining darknesses are. We know at least 4 of them have been trapped inside a portal between worlds (but will likely escape somehow in the future) and then there's one more unaccounted for.
As for the dialogue from Back Cover between the Master and Luxu regarding the box... When the Master whispers to Luxu in that scene, I imagine he said something along the lines of, "this box holds/will hold essences of pure darkness and sin." I think to something like that Luxu's shocked reaction of "But why?" makes a lot of sense. At that point it would make sense for Luxu to be concerned about the Master keeping a box filled with darkness and sin. What makes this all even more interesting is how the Master responds to Luxu very ominously when he says "You'll see..." I'm getting a little ahead of myself, but to even further push this theory past the point of any hard evidence, I'm thinking that perhaps once all of the darknesses are returned to the box they'll form into a weapon similar to the X-blade which would explain the "X Super" written on the top of the box. Again though, that's really pushing it but that's my current head canon and perhaps the Master's true goals aren't to defeat darkness but rather to wield it as a weapon.
And finally, back to the four darknesses who have been trapped between worlds in the portal with the player character... I think that the player character might pull off something similar to what Sora did to help Ventus complete his heart so that he could wake up in BBS on destiny islands. Perhaps Xehanort was born without a heart or with a weakened one, hence the anagram "No Heart" that people toss around. The mother didn't know what to do and so she gave the child up in the hopes that they would awaken on Destiny Islands (somewhere that seems to be frequently associated with awakening of characters). The player heart BECAME Xehanort's heart at Destiny Islands and allowed him to truly come to life. The player's heart has been shown to be fairly resistant to the darkness, after all, and perhaps Xehanort would use that aspect of the Player's heart to be able to control the darkness without it inhabiting his heart.
So yeah, those are just my thoughts and theories on the box + a few other things. Let me know what you think, especially the theory on the box because to me this hits the nail right on the head!
