The Union leaders have finally come face to face with Strelitzia's killer in Darkness. The entity appeared before them after finally being able to separate itself from Ventus' body. Ven blacked out in the process, but the rest of the Union leaders have given Darkness their full attention, including Ephemer and Lauriam, who were on the cusp of battling after the latter attacked Ven with intent to kill. At the moment, the two sides — Darkness and the Union leaders — stand in the calm before the storm.
The critical events of Kingdom Hearts Union Cross quests 970 through 976 exist as the prelude to Union Cross' Final Chapter. In other words, these quests are the penultimate set the game will receive before it reaches its inevitable conclusion after five years. This writing performs a recap and interpretation of these quest's events to clarify the Kingdom Hearts Union Cross storyline. With that in mind, expect to find spoilers ahead.
Confrontation: What is Darkness
Darkness' looks and sounds the way it does so that humans like Brain can comprehend it. This is how Darkness explains its appearance to the group after Brain remarks that he didn't expect it to look like a cliche. It's named Darkness, and it looks exactly like what anybody would expect: a 3D silhouette or a shadow standing up. According to Darkness, though, it has no real form to speak of. It's invisible because its kind mostly goes unnoticed. Whenever that changes, it takes on a shape and voice that beings like humans can understand.
As for what it wants: nothing; it simply exists. It does what it does out of the pure instinct to do so, not because it wants or needs. It understands that this is a hard concept for humans like Ephemer — who asked the question — to understand because humans typically act with a greater goal in mind, but Darkness doesn't. In layman's terms, it's chaotic evil and simply causes chaos for the sake of causing chaos.
As if to prove Darkness' point, a series of misunderstandings between Darkness and the Union leaders follow this explanation. Lauriam doesn't understand how Darkness' actions don't serve a greater goal if it targeted Strelitzia. He doesn't understand what other reason the entity would have for attacking her, so it elaborates: It killed her because that's what Ventus wanted. Of course, none of the Union leaders accept this answer. Skuld especially refutes this and defends Ven's character.
In her rebuttal, she points out that Ventus didn't even know Strelitzia, and even if he did, he's not the type of person to wish death on someone, but this isn't what Darkness meant. Skuld is correct that Ven and Strelitzia were strangers and that he didn't personally wish her misfortune. However, Ventus wanted power, and Darkness gave him that by killing Strelitzia and giving him her title. Union leaders are considered the top five most powerful Dandelions, both in status and in strength, and now Ventus is one of them.
Again, Skuld refutes this, and so does Ephemer. They don't believe Ven is power-hungry, and even if he was, he wouldn't go so far as to take that power from someone else, but again, they're missing the point of Darkness. It sees the world from its perspective, not Ven's, and the way it sees things, power is power. How it's obtained doesn't matter. For it, killing a Union leader so Ven could feel powerful is fine. In other words — as Lauriam now suspects — Darkness would have been fine with killing any of them to make Ventus a Union leader. It didn't have to be Strelitzia.
Already fuming, this sets Lauriam off. He springs at Darkness to attack, but it's useless. The entity brushes him aside with enough force to smash him against the wall and knock him out cold, leaving only Brain, Ephemer, and Skuld left in the discussion. Brain, in particular, wants to use the opportunity to ask Darkness a few questions, and it permits him to do so. He starts, of course, by asking about Ven. He wants to know why most of Darkness' actions have 'benefited' Ven despite its otherwise unfeeling personality.
Darkness explains that it's focused on Ven because of the Book of Prophecies. To Ephemer's surprise, Darkness read the Book — at least the parts concerning it — as its pages filled out, which implies that it read it alongside the Master of Masters. The Book claims that Ventus will be a vessel for Darkness in the future, so it just decided to make him one now. Regarding how it read the Book alongside the Master: the two are old friends, which clarifies whom Darkness referred to in "Maleficent's Escape." That said, Darkness and the Master are not on the same side, as Darkness does not need to ally with people.
In Brain's follow-up question, it asks Darkness why it decided to show itself now after hiding for so long, but Darkness corrects him. It was never hiding; its kind just always works in the shadows. The only reason they can see and hear it now is that they finally acknowledged its existence, hence why it took the form and voice that they're all currently perceiving. Darkness has no real form. They're an abstract existence given shape by those perceiving it.
Brain picks up that Darkness refers to itself with the group pronoun "we" and, by extension, prompts it to confirm that it exists as more than one entity. This explains how it managed to reside inside Ven's heart and escort Maleficent at the same time. It also implies that Darkness exists as something of a hive mind, as Maleficent's Darkness also claimed to have read the Book of Prophecies in "The Union Leader List."
Now armed with the understanding that Darkness exists as more than one entity, Brain, for his last question, has it confirm for him if it's the only one in the room, and once it does, he draws his weapon for the first time, surprisingly revealing that he wields Master Eraqus' Master Keeper Keyblade. Knowing all he needs to know, Brain rallies a shocked Ephemer and Skuld and then launches the attack that starts the final battle between Darkness and the Dandelions.
Confrontation: Keep Watch, Nothing More
The Master has a task for Luxu since he's so worried about the Dandelions. Now that the latter knows what Darkness is capable of, he's nervous over what will happen to the group if they confront it. The Master tried reassuring him that the Book of Prophecies claims the Dandelions complete their mission, indicating they survive. But then he stated that the Book was a long read, so he didn't bother keeping track of exactly who survives, which triggered Luxu's anxiety again. Thus, the Master proposes this: It's Luxu's role to keep watch, so that's what he should do: watch them. But that's it. He can't personally interfere. No matter what happens.
Kingdom Hearts Union Cross is on Android and IOS.