Mortal Kombat has a pretty long and convoluted lore, which is fairly normal for a franchise that has received multiple installments in nearly three decades. Trying to keep track of the canonical storyline can be incredibly tedious, particularly when accounting for the expansive roster of characters. There are several small but crucial events that can easily become overshadowed and hence, the great joy in learning about them for the first time.
Princess Kitana lost her realm of Edenia to Shao Kahn when she was just a child. Despite growing up as his stepdaughter and not knowing the truth, she always dreamed of a time when her world would be rid of the constant wars and her people would be allowed to enjoy peace. She eventually did learn about how Shao Kahn invaded and killed her real father, the late King Jerrod, which made her switch sides in the hopes of liberating Edenia.
Much like how it is in real life, Kitana was never able to triumph over evil. She did manage to free her home world from Shao Kahn in Mortal Kombat: Deadly Alliance but only to face a new threat under the banner of the sorcerers Shang Tsung and Quan Chi. If not them, then there were others like Onaga and Shinnok. When it seemed like everlasting peace would remain a dream for Kitana, she finally did win in the end.
Edenia thrived once more as a beautiful realm and Kitana served it as its ruling queen. Her enemies had all been defeated and an alliance with the other realms ensured that evil would never return. Hence, the long-running canonical storyline ended with Kitana achieving her dream. She was, in a way, the victor of Mortal Kombat.
However, this was when the sands of time shifted and all that Kitana had earned after a lifetime was turned to dust. Before running through what happened, it is important to note that there are two timelines in the Mortal Kombat lore. The first, which is refereed as the original timeline, is the one that has been running since the start. The second, which is referred as the current timeline, is the one where Raiden changed the past by sending a message to his past self. Both are connected and canon.
It was prophesied a long time back that the constant fighting and emergence of new powerful fighters would eventually become too overwhelming for the realms to handle. This point was reached in Mortal Kombat: Armageddon where pretty much every single fighter to ever appear in the Mortal Kombat universe clashed together in a massive battle royale that threatened to rip part reality and bring about the apocalypse.
Blaze was a fire elemental created by the Elder gods for just this event. His sole purpose was to appear when needed and destroy as many powerful fighters as possible to bring balance back to the realms and stop Armageddon.
Blaze began his duties in Mortal Kombat: Unchained by luring warriors to the final battle where he would be able to finish them all at once. This was when he appeared before Kitana and warned her about the upcoming apocalypse. She was told to gather an army to take on the banded forces of evil when the time came, which only left Kitana frustrated over how she would never see an end to war. However, Blaze promised her that if her side won, she would finally achieve her life-long dream of everlasting peace.
With newfound hope, Kitana returned in Mortal Kombat: Armageddon to fight alongside Edenia. She was killed in the final battle alongside all the rest, leaving only Shao Kahn and Raiden standing at the end. In his final seconds, Raiden reached for his amulet and spoke an enchantment before being finished by Shao Kahn. The emperor, now the most powerful being in all of the realms, went on to completely destroy Earthrealm.
It appeared like Kitana had failed to fulfill her lifelong dream. However, what she did not realize was that when Blaze promised her everlasting peace, her victory was not meant at the Battle of Armageddon but afterwards.
The enchantment that Raiden spoke while grabbing his amulet sent a message to his past self, which created an alternate timeline. The canonical storyline until Mortal Kombat: Armageddon was reset and the events of the first three installments (Mortal Kombat, Mortal Kombat II, and Mortal Kombat III) began to unravel once again but with Raiden knowing about how Shao Kahn wins in the future. Hence, his new mission now was not to win the Mortal Kombat tournaments but to make sure that they all avoid the same fate.
This current timeline was, however, not fair to Kitana as well. She fought on the side of Earthrealm against Outworld in Mortal Kombat 9 and died at the hands of her resurrected mother, Queen Sindel. Her soul was later collected by Quan Chi and brought back as an evil revenant to serve him in the Netherrealm in Mortal Kombat X.
It was during her transformation that a startling truth was revealed. Kitana dreamed herself walking the streets of a magnificent city. This was Edenia, now free from Shao Kahn and free from war, and she was its ruling queen. Kitana realized that this reality was from the original timeline where she somehow managed to survive the Battle of Armageddon and banded the surviving realms together to defeat Shao Kahn once and for all. Edenia had achieved its everlasting peace just like Blaze promised her but due to Raiden changing the past, Kitana had lost it all, more so than ever before.
When Kitana awoke from this vision, she found herself in the Netherrealm as a revenant. She had not only lost her realm but also her humanity, and she despised Raiden for it all — ruining her once chance of everlasting peace.
Kitana currently rules over Netherrealm as its empress alongside Liu Kang, also a revenant. Mortal Kombat 11 will reveal how she proceeds further in the canonical storyline.