The death of Organization XIII?

well weve figured out xibars axels and saixs so far oh yeah and xemnas and of course xion, then theres roxas

Lea, Sai, Ion, Ansem, Sora, and Braig

 

The way they died and most of their real names can be found in various "Secret Ansem Repots" from KH2. They describe that in an expiriment to study the nature of the heart they removed their own hearts and became Nobodies. that was what happened for the first six members. as for the others, their life is still a mystery. I think they will have more backstory in future games.

 

at the end of BBS didnt Lea and Sai join on there own, cuz they looked up at the castle and say something about it and started walking torwards the door

cuz like i think they voluntierd or something

 

actually, Lea and Isa were trying to break into the castle for some unknown reason. In the final credits of BBS, we can see Dilan and Aeleus throwing them out. How Lea and Isa lost their hearts is still a mystery as well

 

As I said before.

 

The 6 apprentices to ansem the wise who were the original founding members of Organization 13 were conducting experiments on the darkness within Ansems castle. It seems likely that because of the very nature of darkness that they perhaps underestimated it and inevitably lost there hearts. I think the experiments they were conducting probably caused Radiant garden as a whole to become swallowed by darkness, which would explain why Isa and Lea also lost there hearts despite the fact they were not involved with the others at the time. Seems the most logical answer to me, becayse in KH1 Radiant garden has become hollow bastion, and is over run with heartless and ruled by malificent etc. Something happened to mess the world up and it was most likely caused by the organization members meddlings when they were human.