- Mortal Kombat II: "Serving as an assassin along with her twin sister Kitana, Mileena's dazzling appearance conceals her hideous intentions. At Shao Kahn's request, she is asked to watch for her twin's suspected dissension. She must put a stop to it at any cost."
- Ultimate Mortal Kombat 3: "Murdered by her twin sister Kitana, Mileena finds herself brought back to life by Shao Kahn himself. Her skills as a vicious fighter will be needed to defeat Earth's chosen warriors. Her ability to read the thoughts of her twin sister will enable Kahn to stay one step ahead."
- Mortal Kombat Gold: "Reborn in the Netherrealm and servant to Shinnok since her rebirth, Mileena finds that a coming battle gives her a chance to both escape her fearful servitude to Shinnok and avenge her own death. Knowing Kitana will fight for Edenia, Mileena ensures an easy escape route is left as she moves into battle with Shinnok."
- Deception: "I am a creation of sorcery, the hybrid of a Tarkatan warrior and the Princess of Edenia. My purpose was to eventually replace my... sister... Kitana, from whom I was cloned. Kitana regained her memories, however, and uncovered the plot to supplant her. After Shinnok's invasion, she cast me into her prison, where I remained until Baraka freed me. My hatred for Kitana consumes my every thought. But Baraka tells me that his new lord, the Dragon King, has possession of Kitana's body and uses it as his personal bodyguard. My only chance for revenge against her will be to serve Onaga and pose as the Princess, leading her precious alliance of Edenia and Outworld to their doom."
- Armageddon: "Outworld was MINE! Posing as the Edenian wench Kitana, I gained command of her army and with it took control of Shao Kahn's fortress - all in the name of "peace." I had planned to continue my charade until the Edenian forces could be corrupted enough to follow me as Mileena, the true conqueror of Outworld. But my plans were foiled when the fortress was attacked - Shao Kahn had returned! And he was not alone! As I watched the initial assault from the safety of the imperial balcony, I recognized the two warriors who aided him: Goro, Prince of the Shokan, and Shang Tsung, wretched Sorcerer of Darkness - my creator. They crushed all who defended the stronghold. I hid in the throne room and commanded the Edenian mages to cast a defensive ward upon the main door. It was of no use. Their magic was nothing compared to the might of Shao Kahn. He shattered the door and strode in as confidently as ever. As he stood before me, the two mages rushed to defend their princess, positioning themselves between Shao Kahn and myself. What a surprise it must have been when their own "princess" stabbed them from behind. They fell limp to the floor. Shao Kahn paused, momentarily confused. Removing my veil, I knelt before him, "Welcome home, my master." Shao Kahn accepted my surrender and later ordered me to capture the Earthrealm warrior known as Shujinko. He was to be used as a bargaining chip to help forge an alliance with Onaga, the former ruler of Outworld. I sent the fool an invitation, hoping to utilize his arrogance and pride by acknowledging his heroic deeds. The ruse worked; soon he was at the main gate. Reiko's men, dressed in the armor of slain Edenian soldiers, led him directly to the throne room where he was confronted by the new Dark Alliance. I did battle with him as Shao Kahn commanded, defeating him with surprising ease. He was then cast into the dungeon, where he will remain until Onaga arrives. I do not relish serving Shao Kahn. I am destined for greater things. An entire realm was once in the palm of my hands - and I will not rest until I regain that status! Though it will be impossible to rule Outworld now that Shao Kahn has returned, there are other realms ripe for the taking. Edenia will be mine!"
After Shao Kahn conquered the realm of Edenia and merged it with Outworld, he decided he would keep the former king's young daughter Kitana alive and raise her as his own daughter. Although Kitana grew up loyal to the emperor, unaware that he had murdered her real father, Kahn feared if she should ever discover the truth about her past, she'd turn against him.
Kahn then ordered his sorcerer Shang Tsung to create an evil, vicious, and loyal clone of Kitana who would take her place. Tsung combined Kitana's essence with a Tarkatan's to achieve this purpose. Given the name "Mileena" and introduced as Kitana's twin sister, Mileena's only noticable physical defect was her Tarkatan teeth which she kept covered with a mask. Instead of replacing Kitana as originally planned, Mileena would be used to watch Kitana and make sure she remained loyal to Kahn. As Kahn feared however, Kitana did finally discover the truth about her past and family. Although she continued to feign loyalty to Shao Kahn, she secretly plotted and waited for the right time to overthrow him.
During Mortal Kombat II, Shao Kahn began to grow suspicious of Kitana and Mileena was ordered to watch over her sister. After finding out Kitana was indeed conspiring with the Earthrealm warriors, Mileena attacked Kitana, but Kitana proved to be the superior fighter and killed her. Mileena's essence descended into Netherrealm (Mortal Kombat's hell), fuelling her hatred for her twin sister.
Damned to the Netherrealm, Mileena found herself recruited by the fallen Elder God Shinnok. During Mortal Kombat Trilogy, she was resurrected by Shinnok and sent to Earth to spy for him during Shao Kahn's invasion. She was also granted the ability to read Kitana's thoughts. After Kahn was defeated, Mileena was summoned back to the Netherrealm with Noob Saibot, who was also sent to spy on Shao Kahn.
During Mortal Kombat Gold, Mileena assisted in Shinnok's invasion of Edenia. Seeing this as a chance to finally prove she is superior to Kitana, Mileena allowed her sister to escape Shinnok's dungeons. However, Mileena would again be denied. After Shinnok's defeat, she was again bested by Kitana and secretly locked away in an Edenian prison, perhaps in the hope that she would one day reform.
Mileena remained imprisoned for many years, until the Dragon King, Onaga, returned during Mortal Kombat: Deception and began his own invasion of Edenia. Mileena was freed from her prison by Baraka. She joined Onaga, and was ordered to pose as Kitana in order to mislead the princess' armies while Onaga gathered his strength. Mileena accepted, seeing this as a chance to gain some amount of revenge against Kitana. However, as Mileena began her deception, she also began to consider taking control of the armies for herself.
In Mortal Kombat: Armageddon, Mileena had seized Shao Kahn's Fortress using the Edenian forces, all in the 'name of peace'. Though she did this still under the guise of Kitana, she had decided to continue her charade until the Edenian armies were corrupted enough to follow her under her true identity. Though at first confident that Outworld was hers to rule, Mileena soon discovered that Shao Kahn, alongside Goro and Shang Tsung, had mounted an offense against the fortress to re-instate Kahn's rule over Outworld.
At first, Mileena hid in the throne room, and had instructed her mages to cast a defensive spell on the main door. Their magic, however, proved futile against Shao Kahn's brute force, and soon, the former emperor was face to face with Mileena. The mages then stood between the two in a last effort to protect their 'princess', only to be stabbed in the back by her. Revealing her identity to Kahn, Mileena surrenders to him.
Shao Kahn accepts Mileena's surrender, and then commands her to capture Shujinko, who would be used as a bargaining chip in gaining Onaga as an ally. Mileena then sends Shujinko a false invitation, which apparently works, as Shujinko soon finds himself confronted by the dark alliance and quickly imprisoned after being captured by Mileena herself. However, having tasted power for herself, she is no longer content with being a minion. Deciding that she is destined for greater things, and with Outworld out of her reach, sets her sights on ruling Edenia instead.
She appears in Armageddon's Konquest mode, encountering Taven in the dungeons of Shao Kahn's fortress. She battles the intruder, but ultimately is not successful in preventing his progress. She is later seen with the Forces of Darkness as they march to battle towards the forces of Light. She initially battles Nightwolf rather than Kitana, and as Argus's Pyramid rises from the Earth she is next seen being punched in the face by Stryker during a moment of distraction. Her last sighting is as Shang Tsung is near the top of the Pyramid, as she is seen leaping on his neck and biting him, only to be tossed off his shoulder. Ultimately however, Mileena was killed in her efforts to reach the top of the Pyramid as were most of the warriors present at the battle.
- Mortal Kombat II: "Once thought to be Kitana's twin sister, Mileena is actually a grotesque clone created by Shang Tsung. With Shao Kahn suspicious of Kitana's motives, Mileena seizes the opportunity to attack Kahn and his minions. Caught off guard, they were no match for Mileena's speed. She wins the tournament, and together with her secret companion, Baraka, they rule the world as king and queen."
- Ultimate Mortal Kombat 3: "Winning the third tournament enables Mileena to reclaim her throne as Outworld queen. With the help of Baraka, she then takes both Sindel and her daughter Kitana hostage. Together they threaten Shao Kahn with their lives unless he lures the Earth-born warriors into a fourth Mortal Kombat where Baraka can return and regain his title as the Ultimate Mortal Kombat champion.
- Mortal Kombat Trilogy: "When Mileena is murdered, she finds she is reborn in an evil place called the Netherrealm. Here she accepts her servitude to an all-mighty god known as Shinnok. It is Shinnok who allows her soul to be reborn on the Outworld. Her loyalty to Shao Kahn is replaced by her fear of Shinnok. Mileena plans to overthrow her own father. The ability to read Kitana's mind and predict the Earth warrior's motives enables Mileena to set up her father's downfall. When Kahn is weakened by the onslaught of attacks, Mileena takes the opportunity to destroy her father and allow Shinnok to step forward and take both realms for his own sinister purposes."
- Mortal Kombat Gold:
- (in her throne room, Kitana is watching Edenia through the window. Mileena comes in)
- Mileena: Kitana... I want your status! I want to be Princess of Edenia! It is my right!
- Kitana: You have no right! You are not my sister! You were born of Shang Tsung's sorcery for Shao Kahn! What right do you have to the throne of Edenia?
- Mileena: (dishearteningly, gets down to her knees) No... No!
- Kitana: You are evil and have no place in this world!
- Mileena: You are right, Kitana... But if I have no right to this realm... Then neither will you!!! (uppercuts Kitana, who falls into her throne; advancing towards her, Mileena pulls out her sai) You will die, sister! And I will take this realm for myself! (throws the sai at Kitana, blasting her out the window behind)
- (in her throne room, Kitana is watching Edenia through the window. Mileena comes in)
- Deception: "Because it was widely believed that Princess Kitana had slain her many years ago, none were suspicious of the veil Mileena wore to conceal her Tarkatan features. It was not difficult for her to assume the identity of the princess and take control of her alliance. To further conceal her deception, Mileena gave command of the armies to Bo Rai Cho, and instructed him to lead the attack against Baraka's diversionary forces. Baraka's militia had failed to divert the enemy, and to her surprise, was decimated by Bo Rai Cho's forces. She then realized that she was in control of the most powerful military force in Outworld and Edenia combined.... She had finally achieved her true purpose, her destiny. But Mileena could not continue her charade indefinitely - not as long as Baraka knew the truth. She ambushed him in the ancient Beetle Lair and fed him to a swarm of flesh-eating insects. All hail Princess... Kitana."
- Armageddon: "For an instant, the power of Blaze united Mileena and Kitana. When the energy dissipated, Mileena had become beautiful! But Kitana was horrified to find her mouth filled with elongated razor-sharp teeth. The change in her appearance allowed Mileena to pose as Kitana and finally take her rightful place on the throne of Edenia. She imprisoned Kitana, who went mad in the palace dungeon."