My portrayal is divided among two different timelines
Kitana and Sindel find themselves at the hand of Shao when Kitana is not old enough to process, and such Mileena is made by Shang Tsung at Shao's command to give him a daughter of his and Sindel's own. But she is always seen as lesser. Kitana is always the favorite, the one who is to be groomed in Shao's image. Mileena is second best, never the heir, always told to be more like her sister, admired by none as Kitana was admired by all. The imperfections of her cloning begin to show when puberty comes though, the edges of the blood within her-- Placed there to ensure she would always be like her father and not like Jarrod or Sindel-- begin to show their tainting touch. The blood of Tarkatans starts to show its monstrous self in her. Not all in a sudden moment, but gradually over time. She becomes angrier, grows a shorter fuse. Violence becomes her language of frustration, and bloodshed become her expression. It's something that, rather than be viewed as a weakness or a tragedy as in like Mortal Kombat 1, Shao views this as a strength. She is given praise for this behavior, for becoming more unhinged from the Edenian frame of mind.
The more she embraces it, the more vile her features become, ears so subtly sharpening, grin becoming more unnatural. Teeth grow sharper, like nails in her jaw. By the time she is done growing she is a monster, a full fledged thing fully embracing of her hate, the bloodthirst within her, and the amusement she has in slaughtering those she finds lesser than her. Beneath the surface is a girl soaked in tragedy, given no love or praise except when acting a monster. So becoming the monster she was praised as. Things are dashed to shreds in her heart when her father still continually picks her sister, when she overhears in private conversation between the two that Mileena is still viewed as lesser, even as she's let herself become this monster. Wanting nothing more than to be like her sister, to feel the admiration she knows in her heart she will only ever be the flawed clone...
A monster is a role she can embrace, but she is not without feeling or pain. Envious of the sister all admire.
Much of what MK1 covers tbh.
Mileena is the heir. Kitana's older twin sister, raised and prepared for the throne since a young age. Life is pleasant until the death of her father, Jarrod. Twisted even more so when she is infected with the plague of Tarkat. Though those around her tell her she is more, she cannot help but fear she will become a thoughtless monster. Vicious and without care for whom she harms. Jealous of her sister's level head and composure, she fears what others must think of her. Anxious and paranoid of if they know, letting the viral thoughts of doubters become poison in her mind at times. Worsened only by her being barred from combat of any sort.
What sort of empress can she be if she cannot fight? But what sort of empress can she be if the Tarkat steals her rationale from her?
The help and motivation from her mother, her sister, and... Tanya... help her overcome these fears. She is resolute in her stance, she will not let herself become what she fears she could be.