The "Luxu is Ventus' Dad" Theory 3rd Anniversary Remastered Edition
AKA: Theorizing two characters are related based on their lack of screentime together. Because this post is now 3 years old and we have some more information, I'm finally rewriting it.
Due to the release and completion of Dark Road, we now have a more solid idea of Luxu's personality and can say with relative certainty that we never met the original Braig. That was always Luxu. This was always likely, since as far back as BBS the guy was trying to snag MoM's keyblade back from Xehanort, but Bragi's mannerisms being revealed as Luxu-isms basically confirms it 100%.
This means that Braig's one (1) shown interaction with Ventus is also Luxu's one (1) shown interaction with Ventus.
The interaction goes as follows:
Braig (who is Luxu): How 'bout you leave the popsicle with me, so you can go have your little fight with Terra. You can't be too happy about him deep-sixing your Master. Aqua: Who are you? Braig: You think you two have got some grand role to play. As if. You're only here so that when I finish you off... Terra will succumb to the darkness. So... who wants to go first? Ventus: Shut up! Braig: Oh, so this kiddo thinks he's a full-fledged Keyblade wielder? He's got the angry look down. Aqua: Go ahead if you want to waste your time. Keep trying to drive us apart with your mind games. It'll never work!
Now, this is admittedly not immediately promising, but it actually gives us a lot to work with. It's their only interaction, and it's not exactly a positive one. Even though it's only a bluff, it's still a pretty heavy threat.
[Please note, lots of things after this point, Tumblr has eaten at least once.]
But then, if it's their only interaction, then...
Why does he talk like there have been more?
For that first bit, we know he's not talking about Roxas at that point in KH2: Roxas doesn't glare at him like that during Days.
And the second image is even more interesting. Most people at this point are seeing Xion as Sora. Axel, one of her best friends, sees Sora's face. Xemnas, the guy who's made of Terra (who trained alongside Ventus for multiple years) and Xehanort (who trained Ventus for a time and grew up dreaming memories of someone else’s life that include him) sees Sora's face.
Xigbar sees Ventus. I dunno about you, but to me having one hostile interaction with a teenager ten years ago does not override psychic mumbo-jumbo better than knowing that teenager for a cumulative 4 or 5 years. Even if you have amnesia-- especially by Kingdom Hearts rules, those memories are still there, even if you don't have access to them.
(Before that line, he also comments "What a blast from the past." Wouldn't be a "blast" if they met, like, once.)
And, as of Dark Road, we know that Luxu is willing to let the people he cares about die.
Bragi's confrontation with Baldr begins with him saying "You... It was you..." in reference to Baldr having killed, like, a decent chunk of the people they know. This is not an emotionally detached reaction! Luxu cared about these people! Maybe not as peers the way they cared about him, but he did care! He does care about the ones that are still alive!
So what does he say after revealing his identity and disarming Baldr in a single motion?
He's not gonna do shit! He demonstrably could kick this guy's ass, but he chooses not to. Even though he cares about these people. Even though one of them is the grandson of someone he already demonstrably has a connection to from back before he wound up this jaded. That one, which he later on again did nothing to save, even with more and more reasons to do so stacking up.
Let's go back to the scene where Luxu and Ventus actually, you know, talk to each other, because there's actually a subtler detail in it that I want to talk about.
"Oh, so this kiddo thinks he's a full-fledged Keyblade wielder? He's got the angry look down."
In this one line of dialogue, Braig calls Ventus "kiddo." You might be wondering, "What's the big deal? He calls Roxas that all the time!" Yes, he does. He also calls him "Tiger," and Xion gets called "Poppet," both with notable regularity.
Contrast that with how he talks to, say, Sora. He still talks down to him, but he uses nicknames much more sparingly. In fact, he doesn't use any for Sora until Dream Drop Distance. All through Kingdom Hearts 2, the Organization is trying to stir Roxas' consciousness within Sora, but Xigbar doesn't call him any of the nicknames he used for and around the guy the whole time.
Not until DDD, when they've already given up on that plan. He starts out with a "sleepyhead", but there's a very specific moment I want to draw your attention to. A moment I may have neglected to mention earlier in this post, despite its relevance.
Xigbar comments on the thing Sora does that reminds him of Ventus. Then he calls him "Kiddo." And then he never calls him a nickname ever again. I'm not kidding. Never ever.
We don't see a lot of him interacting with young people outside the Heart Hotel, but we do see once in Kingdom Hearts three he calls the Real Organization's Riku Replica "Kid." Not "Kiddo," but "Kid." An interesting distinction, don't you think?
So, to recap so far: One interaction, yet Xigbar talks about Ventus consistently. He's the only one to see Xion with Ventus' face. He uses nicknames more often on kids that remind him of Ventus, and specifically uses a different variation on a kid that doesn't.
"Okay Ace," you're probably thinking, "I can accept that this proves a connection definitely exists between Luxu and Ventus. But why are you so sure that they are father and son specifically?" Well, I have a few reasons.
We don't technically know how old Luxu is, but he is an adult when Ventus is like 10 or 11. It's not impossible for them to be, like, siblings or something, since some people have kids pretty far apart, but it's not dreadfully likely to me. Based on my own experiences with my big sister, they don't really act like siblings to me, but I suppose that's a personal thing. You could say Luxu "sounds young" in Back Cover, but once you hit a certain point a lot of peoples' voices stay the same for a long time.
Nomura has stated that the next part of the series will be focusing on "bloodlines." We already know we're probably gonna be seeing Eraqus' grandfather in ML and that guy's probably gonna be Brain. Xehanort's already descended from Ephemer. Characters are already descended from each other.
Luxu is short for Luxuria, the sin of Lust. So, from a certain perspective, Xigbar canonically fucks.
