This will be alternate reality, so no canon characters and few canon events exist/are relevant.  Like the original timeline, it begins with a handful of the last of the Keyblade Wielders, the difference being the exact cast of characters, and therefore their actions and fates.  

The order of Keyblade Masters has always had a policy of non-interference in the many worlds that make up all of reality.  When one such master decides that this rule hinders him and his plans, he makes an enemy of his former comrades.  Auldus Vull traveled among other worlds, making allies and forging alliances between powerful figures.  Many worlds have prospered from the inter-world trade that he has allowed to exist, but some have been put under harsh rule of the governors that Auldus has set up.  And a few of the worlds he has visited were consumed by the Darkness, and vanished from existence.  

Auldus Vull has trafficked in darkness, but remains largely uncorrupted, as he allows his subordinates to get closer to it than he ever does.  He gives knowledge of the Heartless, and how to control them, to his more brutal governors.  Auldus himself, however, prefers to surround himself with guards and soldiers borrowed from the worlds under his de-facto rule.  

Our story begins when he personally attends to the world of Sunrise City, where our heroes are from.  It is here that what is left of the Keyblade Masters finally catch up with Audlus Vull, and try to destroy him.  Unfortunately, they are no match for him and the hardened killers that he brought with him from A Galaxy Far Far Away.  They all fall, leaving Auldus as the only Keyblade Master.  Auldus tries to usurp the keyblades of his fallen former friends, but his own experiments with the nature of these weapons only allowed him to save two.  The others dissolved away to somewhere that Auldus would not find them until he least wanted to.  Auldus lamented only briefly, but considered the isolation of two keyblades to be a triumph.  He continued with his business on Sunrise City, but unlike most of the worlds he visited, he made no attempt to make himself known to any of the locals, as he considered none of them to be of any use or importance to him.  

His condescension may turn out to be his doom, however.  The keyblades that he lost find their way into the hands of a group of young novices from Sunrise City, who use them to escape their world’s fate, and seek revenge and justice on Auldus Vull.  

I’m not sure how many people we are looking for, but there’s the opening write up.  

We will be visiting only, or almost only, worlds that have not been seen in Kingdom Hearts yet(Brave, Frozen, Treasure Planet, and yes, in case you missed it above, Star Wars), unless I decide that one of the others would be perfect for our plot needs.  

I’m trying to find a middle ground between railroading the plot(obviously bad) and allowing the characters to drive it(better, but which presents its own problems).  So to this end, I will try to have multiple possible paths that the players can go, but also will be taking the individual characters into account with planning.  My CS will include a “Plot hook” which would be, not necessarily something that your character has going on now(as their world has been destroyed, so it’s not like they have a personal quest to be getting on at the moment) but which is a direction you’d like them to go, or something you’d like to see them accomplish.  With this I hope to weave a plot that works for everyone.  

CS:

Name:
Age: 12-17
Appearance: Though I’m generally not fussy how you do this, I may ask for a new picture just because I don’t like it aesthetically.
Keyblade: 
Fighting Style/specialty: Obviously your character has no martial experience yet, but that will change in short order.  Let me know where you plan to take them for this.  Don't try to make them do too much, this is a specialty.  
Background: Your character’s story is ahead of them, not behind them, so you don’t need to give them a whole novel’s worth of exposition.  Just give us an idea of what sort of person they are, what sort of background and upbringing they come from.  
Plot Hook: What would you like to see for your character?  How can I, as the GM, give you some intrigue that will work well for them?