Report 1, been a long time since Xehanort left his hometown (Destiny Islands, hinted at Report 10) and traveled to various worlds. He destiny was changed when he met his Master and the other apprentice Eraqus, at Land Of Departure which became his 2nd home. During his training, he often wonders about the Keyblade and its real purpose beyond the fact it's used to protect the world from darkness. Out of curiosity, he would often sneak out to other worlds for more knowledge
Report 2, it is told that when traveling around worlds, you need the armor in order to protect yourself from the darkness around. Xehanort decided not, he thinks that if he can control darkness then darkness would no longer be a threat
Report 3, in ancient times, the world werent separated nor protected by light walls. In those time, the world was filled with Light, there are many Keyblade Wielders around, but then people started fighting for Light. Keyblade was originally used to summon Kingdom Hearts, the wielders all wanted to obtain that heart of light, the War was then started. Kingdom Hearts is the unification of hearts, like human and their heart, the world itself has its own heart. In each world, there is a door to that world's heart, if you gather the hearts of all world, you can then complete Kingdom Hearts
Report 4, opening Kingdom Hearts is like creating a new world, this is all beyond human. In short, whoever opens Kingdom Hearts is no longer a Human. All sorts of people fought for the Kingdom Hearts, even unrelated worlds got involved and in the world, the worlds were covered in darkness. The remaining lights from hearts created the present world and to prevent another war, the worlds are all covered by light walls
Report 5, us wielders' duty is to watch over and protect the world, but then, there are little of us left. Besides the world of light, there is also the world of darkness and the layer between the two. The world of darkness is forbidden and it is said that no one has made it out once they are in there
Report 6, there are three types of keyblade, keyblade of the world of light, of the world of darkness, and of one's heart. The keyblade of one's heart is a by product of the war, without it, you cant reach Kingdom Hearts. If to collect 7 hearts of pure light, you can complete the Keyblade of One's Heart, to open Kingdom Hearts. if one could open Kingdom Hearts, it means one can obtain all worlds and people in their hands
Report 7, biggest mystery of Keyblade that is beyond those 3 types, the X(read: Chi) Blade. while The Keyblade corresponds with the Kingdom Hearts, it is a product of human. X Blade, however, co-exists with Kingdom hearts. X Blade is the crossover of a heart of Pure light and a heart of pure darkness. When that happens, Kingdom Hearts will appear. This is not man-gathered Kingdom hearts, it is the Kingdom Hearts with all the hearts of the worlds gathered. This was the cause of the war. Even though the worlds now are all separated, if you can obtain the X Blade, you can gather the hearts of the worlds together to complete Kingdom Hearts, to bring forth the war again
Report 8, Eraqus thinks Light is absolute but Xehanort thinks light and darkness should be at a balance, to maintain the balance of the world. The world now is losing its balance due to the rejections of darkness. Once the light breaks, the darkness will come forth, then the world will need to be reconstructed. Due to the obvious differrenece in opinions, Xehanort and Eraqus had a quarrel and Xehanort departed, drifting to other worlds, his new freedom since he departed from home when he was young. Already being a keyblade master, Xehanort thought of his duty, a successor. However, Xehanort doesnt seem to want to end his life at there, he still has things he wants to see and confirm, but his body is aging as he notices
Report 9, a Keyblade Master has a special ability, it is to extract self's heart or other's heart. Repeat the process and one can live on forever. When Xehanort was young, he dreamt the world's boundary, a world no one has been to, a world no one has seem. If he were to open Kingdom Hearts and create the new world, then a world with equal light and dakrness can be completed. After gathering enough knowledge, Xehanort got a new goal but first up, a new vessel/body. It was then, Xehanort met with Ventus and took him in as his apprentice. It was destiny, Ventus has the potential but at the same time, he is too gentle. Hence, Ventus can not be his new vessel but Xehanort plans to use him for his other goal (ie, X Blade). Xehanort divided Ventus' heart into two, it was then a Pure Heart of Light and a Pure Heart of Darkness were completed
Report 10, as expected, Ventus couldnt take the separation of his heart, Vanitas was successeful born, but Ventus went into sleep. Heart of Pure Light, Ventus, Heart of Pure Darkness, Vanitas, combine the two hearts and the X Blade will be completed. However, Vanitas' Heart is way too strong and Ventus has nearly no light left when his heart broke into two. Xehanort wanted to take him to a peaceful place to sleep, the place that's Xehanort's hometown. Without noticing, Xehanort already at the beach, the same beach where he decided to departs. Ventus can rest here but then, he pulls out a Keyblade, looks like the heart of light is still not diminished
Report 11, Ventus and Vanitas, Light and Darkness are yet at a balance, Xehanort cant train both of them at the same place, Vanitas' darkness will just consume over Ventus. What better place to train Ventus for Light? Under Eraqus, the one that thinks Light is absolute. Eraqus didnt mind the quarrel and Xehanort's departure from way back, instead, Eraqus was happy to see Xehanort again. Eraqus gladly accepted Ventus as his apprentice. Remaining is to wait for Ventus to get his light grow stronger. At LoD, Eraqus also got two other apprentice, one of them, Terra, has the potential and gentle, at the same time he seeks power. The stubbornness to have more power will make Terra to grow darkness, Xehanort decided on Terra as his vessel.
Report 12, The time is here, the Eraqus' Master Exam for Terra and Aqua. Xehanort plans to lure those two away to other worlds which should be easy, but Ventus...... Vanitas can sense Ventus' heart, through Vanitas, Xehanort found out the key to control Ventus, it is, Terra. Ventus looks up to Terra like a big brother, Terra is the one that can move his heart. Therefor, Xehanort decided to separate others and have Terra lone, have the small light (Ventus) to chase after Terra with growing darkness. Because, Strong Darkness makes Light stronger, Stronger Light makes Darkness stronger......With that, everything will interwines and soon the legend/war will appear again...