So far, no other game is of such importance to the mythos of Square Enix's Kingdom Hearts than Union X. A shame, then, that said the story is told on a now-inaccessible mobile game. Nevertheless, footage of the game exists for fans to theorize about, and it's no secret that most of the characters end up having some major importance in KH's lore.

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This article includes major spoilers for Kingdom Hearts: Back Cover, Kingdom Hearts: X, Union X, and Union X: Dark Road as the games have a lot of repeat character appearances.

10 The Master of Masters

A cutscene of The Master of Masters giving Luxu his Keyblade in his laboratory.

Boy, Master of Masters is perhaps the biggest Kingdom Hearts mystery, and so many fan theories abound about who he might be. With the introduction to time travel made in this game, there's no knowing where or when this guy will show up again. But right now, he certainly looks like the Big Bad: he duped the Foretellers into fighting one another in order to let darkness into their hearts.

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Those five hung on his every word, even though he manipulated them into believing the Keyblade War could be prevented. In Union X, Master of Masters has long since peaced out, which is why he ranks so low here. But his influence is felt through the actions of Luxu and the Foretellers whose combined efforts bring their world to war.

9 You (The Keyblade Wielder)

A large gathering of keyblade wielders and the player standing before Master Ava in town square.

Boy, is it weird to have a self-insert character in Kingdom Hearts, especially one that has so, so much relevance to the plot. In fact, Kingdom Hearts may be one of the few games wherein the height of your OC's involvement is "raised the series' main antagonist". In this game, you play as a Keyblade wielder unwittingly thrust into politics and corruption, forced to fight your mentor and friends in a war that nearly kills you.

Your character has a few surprising moments of individuality. Most notably, they sacrifice themselves at the end of the game, keeping the darkness from leaving the data world and dying in the process. They're fun and kinda cocky, and legit save the world. They're no higher than this on the list due to their nature as a self-insert.

8 Master Ava

A cutscene from Kingdom Hearts X of Master Ava standing before a fountain

Master Ava instills in the Union leaders a sense of purpose that drives them forward, even after learning the truth about their missing memories from the Keyblade War. While the other unions are imploding, Ava's life goal was to protect the Dandelions from being caught in the crossfire.

What makes her great is, despite performing the task given by MoM, Ava took plenty of liberties to protect the Dandelions from the foretold traitor, Luxu. She never stopped hoping that there was a way to change fate, choosing to give the Union leaders a Book of Prophesies. She doesn't rank high since she's physically absent from Union X, and her battle with Luxu did begin the war.

7 Luxu

Luxu stands on a cliff talking to a dark shadow

Xigbar revealing himself as Luxu was one of the series' most iconic moments, and we're dying to learn more. Despite his suspicious appearances, Luxu only does what he does in an effort to save the world. Per the Master of Master's bidding, he's gotta ensure the Union leaders become vessels for darkness while trapped in the data world.

He's initially quite reluctant, and feels bitter about the many sacrifices made during the Keyblade War as part of the MoM's plan. Luxu's one of the coolest characters in the series since he's the most prevalent, showing up in some form in practically every game. He ranks low here since he's pretty passive, letting Darkness do its thing in the data world before dipping with Brain.

6 Strelitzia

Strelitzia and Lauriam sit together in a field of colorful flowers, chatting.

Strelitzia, we hardly knew ye. The responsibility of being a Union leader left her with guilt about those who hadn't been chosen to survive, which speaks to her kind nature. Despite not getting a lot of time with her, Strelitzia's death is pretty sad, as she mourns never speaking to you when she had the chance. Darkness killed her to take her place as Union leader, when all Strelitzia had wanted to do was warn the Player about the war.

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This is Kingdom Hearts, so Strelitzia isn't truly dead. She shows up as a freaky data ghost, as well as clothed in a white version of the MoM's coat in Lauriam's dream. She's in the Quadratum, where some characters go when they 'die', and may act as Sora's guide there. So she might be pretty low on the list now, but we're sure she's going to play a significant role in the coming saga.

5 Ventus

Ventus and Ephemer shake hands and smile at each other in the Keyblade War battlefield

Poor Ven, this kid just can't catch a break. He's not even supposed to be one of the Union leaders but gets there because he unwittingly kills Strelitzia. The guy doesn't even know it until it's spelled out for him that he's been made into a vessel for Darkness, and then that mess with Vanitas in BBS suddenly makes sense. It's honestly gut-wrenching to see him used like a puppet for such a horrible act, and then become stricken with guilt afterward. He ranks low because he is a bit of a liability for a while.

But Ventus ain't got time for self-pity. He uses his power as a being of pure light to defend his friends from Darkness, so they can escape the data world. Ven is as pure and as tragic as we've ever seen him, but we can't wait to see him reunite with and potentially avenge his Union buds.

4 Lauriam

Lauriam Elrena Street Dialogue

It should be no surprise that Marluxia's somebody was the coolest guy around. He's originally blasé about his role as Union leader, pictured here with another familiar Organization XIII member. But the murder of his sister sobers Lauriam up quite a bit.

His whole character arc, centering on the love and loss of Strelitzia, peaks when he nearly gives in to darkness and attacks Ventus. But Lauriam snaps out of it with the help of his friends, and swears to always remember them. His selfless, kind nature ranks him high, but he hasn't had any big character moments (yet).

3 Skuld

Ephemer And Skuld are sitting in capsules, chatting

Skuld is a faithful companion in both Kingdom Hearts: X and Union X, basically saving your character from death by bringing you to Master Ava in search of Ephemer. Skuld's stalwart morals define her; she despises keeping the Dandelions in the dark about the Keyblade War, even if it has to be done. She and Ephemer have this cute puppy love thing, and her supportive friendship with Ventus is sweet, especially when she's protecting him from an angry Lauriam.

Otherwise, Skuld loses points since she doesn't have many big moments as a character, most of them in tandem with Ephemer or the whole group. But she and Ephemer are the only ones who actually see Daybreak Town fall to darkness, and later, the woman holding baby Xehanort looks an awful lot like her. The series, it seems, isn't done with her.

2 Brain

Left to right: Ephemer, Brain, Skuld and Ventus chatting on a cliff

Braig, I mean Bragi, I mean Brain was recruited pretty reluctantly, a smart kid with little desire to become somebody's pawn. He's a team player though, despite immediately suspecting their superiors' ulterior motives.

This smartypants leads the investigation into Strelitzia's disappearance, figures out they're all in the data world, and pries apart MoM's purpose for the Union leaders. He's level-headed and pragmatic, his efforts saving the crew from darkness, but loses points for falling into Luxu's clutches.

1 Ephemer

Ephemer in KH3 smiling back toward the camera, surrounded by white light

Ephemer is the leader among the Union leaders, faithful to Master Ava's teachings on how to lead the Dandelions after the war. He's the voice of good and truth throughout Union X, even if he's faced with the same doubt and grief as the others. He defends Ventus against Lauriam's wrath and sacrifices himself, so the others can escape Daybreak Town.

After surviving the collapse of Daybreak Town, he goes on to find Scala ad Caelum, and passes Brain's keyblade down onto Eraqus. Last on his list of good deeds, he and the fallen Keyblade wielders help Sora defeat Ephemer's great-great-grandson, Xehanort. No other long-standing character has stayed true to the light like Ephemer, which makes him one of the most underrated.

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