During Nikita's time in Division , she was once on an operation were they raided the Udinov . Knowing that one of the targets was a child, Nikita couldn't bring herself to kill a child. So, during the raid Nikita rushed to Alex's room, but killed the father, saving Alex at the cost of her father's life. Forced to return to division, she left Alex under the care of one of her father's associate. However, he sold her to sex traffickers. Eventually Alex escaped her captors but remained addicted to the drugs they had given to her to keep her high.
After fleeing division, Nikita kept searching for Alex for two years, until she found Alex, who was trying to buy "Smack" from a local crackhouse for a fifty. However, her dealers tried to rape her, saying "you make us feel good, we make you feel good". Nikita saved her, and took Alex. In her lair, she put Alex in a portable Sauna until she was unaddicted, a process she had experienced first-hand. Afterwards, she took care of Alex. One day, Nikita found Alex unconscious on the floor after shopping for clothes. Seeing the pill bottle nearby and realizing Alex had a weak pulse, Nikita put two and two together and saved her by inducing vomiting. However, Alex was ngrateful and told Nikita "I have nothing to live for. All the people I love are dead." At that point, Nikita revealed o Alex she had been looking for her for 2 years and that she knew who killed her parents, assuring her she had something to live for. Nikita explained to Alex about Division and Alex joined Nikita in her crusade to take down divison. Nikita trained Alex, teaching her everything to prepare her for her infiltration of Division.
After successfully infiltrated division from the inside,Alex was communicateing with Nikita under the raider which revealed in the pilot,I n Resistance,showed her concern for Alex after Alex escape from a terrorist,and contacted Nikita to help her, Nikita revealed that she went through the same thing with division,fearing the consequences, Nikita decide to come for Alex but Michael arrived before her, Nikita left after she became sure that Michael gonna keep alex safe, throughout the first part of the season thanks to Alex communicate with Nikita under the raider from division they both successfully sabotage , a lot of the division operation however it was short lived after Birkoff discovered the shell program that both Nikita and Alex, were secretly communicating,during the mission to assassinate the leader of a crime syndicate named Zoman, Alex nearly blowing her cover, Nikita allow Alex to capture her,so they ca n both escape afterwards. While Amanda interrogates Nikita, trying to make her reveal the identity of the mole and the location of the black box she has in her possession,however Alex plants explosives as a diversion,so Nikita can escape,after Nikita escapes she tries to convince Alex to come with her since Alex's identity as the mole might be in jeopardy,however Alex maintain in division pinning,the mole on Thom who Alex killed,while promising Alex that Division gonna pay .
After Alex became an agent,Nikita and Alex reunited again,after reunited Nikita realized that Nikita realized that Percy planted a kill chip inside Alex,Nikita never told Alex about it but Nikita stops the kill chip,both Alex and Nikita worked together on mission to sabotage some of division's mission throughout the first season Nikita always looked out for Alex and always came for her in time of need,like when Alex's past came back to hunt her,was kidnapped by her old captors,she teamed with Michael who was unaware back then,about their partnership,and tries to get Alex out of division.
However the relation took a turn for the worst when Amanda and Percy discover that she is the mole Percy show Alex recording from the day of the raid on Alex's family house show Nikita was the one shooting Alex's father,when Alex confronted her about her father's death resulting in Alex shooting Nikita,latter Alex came back and confronted Nikita telling her that she can't trust her anymore,and having her own crusade now is to go after the man that is responsible for the death of her family however they were interrupted by division attackers after escaping both Alex and Nikita went on separate ways shattering their relation .
Alex was captured by Amanda's men and brought her to oversight Alex made a deal with oversight that to help them to stop Nikita in return they well help her to take down Sergei Semak.
After Alex and Nikita's relationship shatters during the first course of the second season,Nikita showed remorse regretted about lying to Alex.Alex started working with division to stop Nikita in return they well help her kill Sergei Semak,Alex and Nikita confronted each others which led to a fight ensue leading Nikita breaking Alex's arm and shooting her before shootin g her Nikita stating "remember this i did this because i care".
Throughout the out the first course Nikita and Alex have been against each other with division with Alex assets to stop Nikita but with no avail,however their relation start to take back some importance in "Partners", when Nikita was against the idea of killing Alex,stating that she doesn't deserve to die,after a shooting ensue between Gogol and division, Kelly made a move on Alex resulting in Nikita killing her former partner,Nikita apologized to Alex for lying to her stating that she should have treated her like a partner,after that Alex showed a good faith allowing Nikita and Michael to escape.
And also in 343 Walnut Lane,Alex was the one that warned Birkoff about division faking a father for Nikita.
In Pale Fire Nikita and Alex once more cross path each other in Russia in different missions,Nikita trying to steal the Black Box while Alex attempt to make her move on Sergei Semak,Nikita decide to put grabbing the Black Box on hold,to help Alex to save her mother,they put a plans but things didn't go as planed due to Alex being captured by Ari's men,Nikita saved Alex ,but Alex suffered a minor injury in her hand,Alex surprised that Nikita was willing to go back for Katya which make Nikita stating "I told we're gonna get you're mom out tonight".After going back for Katya's realizing that Katya was the one that set up Alex for Ari's men believing that her daughter was brain washed and her affair with Semak which led,Alex to be heartbroken and Nikita being angered by Katya's comments,which resulted in Nikita trying to take Katya by force under gunpoint,Katya screamed for help,which resulting in a shooting to ensue and Alex coming back for Nikita,fighting together through Semak's guards escaping the Udinov estate.
Later Alex was depressed about the truth about her mother Nikita comforted her telling her that her mother was misguided and not to give up on her,Alex stated that she also tried to reach out for Katya after everything which made Nikita telling Alex that when you give people second chance sometime they surprise you.After this ordeal Alex and Nikita reconcile with each other.
In Sanctuary Alex stayed with Nikita in the beach house,Alex still depressed after hearing the truth about her mother affair with Semak,she tried relies on drugs again but caught by birkhoff,who told Nikita about it,she comforted Alex and told her about her history with Carla,and how Carla leaving Nikita brook her hear she eventually told Alex the same lines that Carla used to tell Alex "you can stay this is a safe place",later Alex and Nikita were seen talking Nikita opened up to Alex about the relationship issue with Michael,and also talking about Belarus both nearly gotten each other killed which they both laughs about it.When Sean tried to kill Nikita,Alex was the one that saved her,with the help of Michael and Nikita mange to capture him.
In Clean Sweep,after hearing about Percy's plan to take back division,with operation clean sweep,Alex suggested that she can stop the trigger from inside division,Nikita was reluctant but she eventually agrees,nowing that alex is the only one who can stops clean sweep.
In origins when Alex was prepping herself to reveal her identities,she and Alex talk stating "i got you're back always",also when Sermak men start to attack Alex,Nikita black mailed Ari to assist Alex escaping or she well reveal ari true intentions to everyone including Semak,which resulting Alex,escaping eventually thanks to Nikita.
In Arising Nikita and Alex reunited after hearing about Semak's death,Alex wasn't happy about it,Nikita comforted her telling her that revenge always doesn't turn the way that she expect .During the second season Nikita and Alex along with Michael and birhoff works together to stops division.
In wrath Nikita and Alex bounded while running in the beach talk about the future and what they plan to do next, also Alex helped to save Nikita and Michael.
In Shadow Walker,it was stated by Alex that Nikita is the one that like to know about Alex's personal life when Michael asked Alex about her relationship with Sean.