Mortal Kombat 1 is both a reboot and a sequel, following the end of MK11, in which Liu Kang became the God of Fire and reshaped reality. But in his new peaceful Utopia, Mileena is still a Tarkatan hybrid, leaving fans wondering why Liu Kang didn’t make her twin sister Kitana once and for all.
Mileena’s history is tragic. She was born in Shang Tsung’s flesh pits under the orders of Shao Kahn, who combined Kitana’s DNA with Tarkatan blood to create a superior fighter. This twisted beginning led Mileena down a bloodthirsty path to kill Kitana so she could take her place. Eventually, in the new (now old) Mortal Kombat 9 timeline, she became the ruler of the Outworld and forged her own story, only to be overthrown by Kotal Kahn. In MKX, she valiantly pushed back for her reign, but died at the hands of D’Vorah. But with a new universe comes a new Mileena and a new chance for peace.
It looks like in Liu Kang’s Fire God universe, Mileena and Kitana are not rivals or enemies, much like Scorpion and Sub-Zero. This may be Liu Kang’s attempt to right the wrongs of the previous two timelines, but it still raises the question of why Mileena isn’t just Kitan’s twin. One theory suggests that Liu Kang cannot reshape reality in minute detail, he can only draw broad strokes. This means that Mileena would remain the same, maybe even have a similar origin story, but she wouldn’t end up lusting after Kitana’s death.
Supporting this theory is that we find out in MK11 that Kronika was unable to control the universe to this extent. So it’s likely that Liu Kang is simply recycling the tools at his disposal to try and bring peace, but when your tools are soaked in the iconic blood, bones, and guts of Mortal Kombat’s victims, violence and chaos are inevitable.
Another theory related to this is that there are constants in the Mortal Kombat universe. Think of the fixed points in Doctor Who time that no one, not even the Time Lords, can change. In this case, the events of Fire God Liu Kang cannot be overwritten. Mileena’s birth as a half-Tarkatan at the hands of Shao Kahn may be one such event, and Liu Kang has no say in the matter.
The lesser of the two theories is PepperBun28’s theory, which claims that Liu Kang put the pieces back together into a new order and then sat back to see how things would play out. He wanted to see if Mileena and Kitana could get along without changing too much, observing their behavior. It’s definitely possible, albeit a bit creepy.