Neo is seen working with Cinder after Roman's incarceration. She fights as the fake Haven team's fourth player in the Vytal Festival, and pilots the Air Bus ambulance taking Mercury Black away after his match against Yang.
Neo was an affiliate of Roman. She seemed to be the only person Roman did not regard with utter contempt and disdain, and she quickly got him out of danger on multiple occasions.
They were also shown to work fluidly together in combat, working off one another's attacks in a very organized display. This is depicted during the events of "Heroes and Monsters", where both fight against Ruby Rose and overpower her with relative ease.
In a video chat interview, Miles Luna claims that the production for RWBY has differing ideas as to what Neo's relationship with Roman is, "maybe she has an unhealthy crush on this older guy," he continued, "other ideas are like, maybe it's straightly platonic." The exact specifications of their relation has never been nailed down, but there was certainty that Neo is Roman's shadow and he has likely never had romantic feelings for her. In both this video chat and the Volume 3 Cast Commentary, Miles compares their relationship to that of Harley Quinn and the Joker from DC Comics, in that it's not a healthy relationship. In addition, Lindsay Jones also compares their relationship to that of a daughter and father, with Miles agreeing.
Monty Oum has said she was designed due to the need for Roman to have a right-hand woman. In the non-canon RWBY: The Official Manga, Roman is shown to threaten Neo with killing her if she interfered in his fight with Ruby, showing a willingness to execute her. Despite this, Neo is also the only character towards whom Roman has exhibited any genuine concern, as he cried out in horror when Ruby activated her umbrella atop an airship during the Fall of Beacon, sending her flying.
In "The Coming Storm", it is revealed that Neo has not gotten over Roman's death and she wears his hat in remembrance of him. She attempts to exact vengeance on his behalf by trying to kill Cinder, whom convinces her to instead target Ruby, citing she was the true reason why Roman was killed.
Neo's is said to be sweet, loving, and loyal, though her loyalty is limited only to Roman himself.
Neo is part of Cinder's team during the Vytal Festival Tournament. Whilst they have not been shown interacting much, she apparently works well with her as a team in combat.
Neo's affiliations with Cinder's faction continued even while Roman was imprisoned by the Atlas military.
In "The Coming Storm", Neo wants revenge on Cinder who she believes is responsible for Roman's death. After Cinder reveals her Maiden powers, Neo agrees to work for her to kill Ruby. They later seal the deal with a handshake in "The Grimm Reaper". In "Our Way", Neo impresses Cinder when she demonstrates her Semblance on a Mistralian airship.
Neo has displayed exasperation when dealing with Cinder, usually rolling her eyes and taking her time while giving Cinder a response. Furthermore, while Neo was visibly happy when working with Roman, she is shown to be often annoyed and somewhat resistant to Cinder.
Cinder has been able to take advantage of Neo's anger to manipulate her, using the girl as a tool to regain favor with Salem by promising her vengeance on Ruby. During "Out in the Open" when Neo attempted to rebel against her orders, Cinder was able to get her under control by assuring her she would get to kill Ruby after they finished her mission. Though once Neo does procure and present the Relic of Knowledge in "The Enemy of Trust" she receives not a hint of gratitude from Cinder, annoying her even further.
Neo and Ruby first see each other in "Painting the Town..." when Neo rescues Roman with her Semblance.
Later, when she discovers Ruby on their stolen airship, she sends Roman a message with Ruby's picture and the text "Guess who?"
When the two fight, Roman later joining in, Neo is easily able to disarm and overpower Ruby. When it looks as though Neo is readying to kill her, Ruby saves herself by pressing Neo's umbrella open and sending her off the airship via the high winds.
In "The Coming Storm", Neo is convinced by Cinder that Ruby is the one responsible for Roman's death, prompting her to team up with the Fall Maiden to hunt down and kill the Huntress.
Neo infiltrated Atlas with Cinder in order to have her revenge on Ruby. She aided Cinder by spying on everyone during "Cordially Invited", and smirked as she watched Teams RWBY and JNR go off to fight the Grimm in "As Above, so Below". Later that night, Cinder ordered Neo to take the Relic of Knowledge from Oscar, however Neo immediately became upset and took on Ruby's appearance to illustrate her wish to prioritize her revenge.
Although the two have only interacted in battle, Neo seemingly enjoyed fighting Yang, even to the extent of toying with her in the midst of combat. Yang's temper came out in reaction to this and Neo used it to her advantage. After the battle ended, Neo gave a sadistic smile as she prepared to kill Yang.
Neo attempted to convince Team JNR she was Oscar to allow her to escape with the Relic she had stolen, before Oscar himself arrived and destroyed the illusion. Upon seeing Neo's true form, Jaune appeared upset, and after confirming he knew of Neo, he explained he had 'not heard good things' about her. They proceeded to fight, and Jaune was able to use his gravity Dust-empowered shield to protect Oscar and blast Neo away, though he did no lasting damage. After stealing back the Relic, Neo, under the guise of Nora, met Jaune in the halls, but easily evaded him escaped.
Neo impersonated Oscar after taking the Relic from him and was discovered by Nora, who excitedly ran to meet Neo before Oscar arrived and destroyed her illusion. Nora immediately and angrily identified the girl as Neopolitan, apparently already aware of Neo's identity. While they fought, Nora took two shots at Neo, which were blocked before Neo took her out. Later, Neo took on Nora's appearance to steal the Relic from Oscar and prevent Ren from attacking her.
Like the rest of Team JNR, Neo properly met him during her attempt to steal the Relic from Oscar, when the team showed up to fend her off. In the ensuing fight, Neo silently, yet blatantly, mocked Ren feigning shock before gleefully dispatching him. Neo met him again later in the fight while impersonating Nora, and used her disguise to manipulate Ren into preventing him from attacking, and thus allowing Neo to escape. Afterwards, Ren was seeing crying out of guilt.
In "No Brakes", Neo immediately became fearful and retreated from the train car after Raven arrived via a portal to stop her from killing Yang. In the Volume 2 Director's Commentary, it is stated that she retreats because she can tell that Raven is someone she cannot defeat. This is evidenced by her opponent's superior speed and Omen, her telescopic blade.
Neo was tasked by Cinder to locate the Relic of Knowledge, which she found was in Oscar's possession, though she seems to have no personal feelings towards Oscar. When Cinder charged Neo with taking the Relic of Knowledge from Oscar, she rebelled, apparently seeing the task as less important than her revenge. However, after being assured she would get to kill Ruby, Neo relented and went after Oscar.
Offscreen, Neo attacked Oscar and stole the Relic before impersonating him in front of Team JNR. However, Oscar had not been incapacitated and attacked her, delivering the first clean hit to Neo in the series, shattering her illusion and revealing her identity. This also knocked the Relic from her and Oscar took it back, telling the rest of the team what had happened and calling Neo a 'crazy girl'. After dispatching Ren and Nora, Neo fought with Oscar, attempting to get the Relic from him, but failed as Jaune stepped in and blasted Neo away. The group proceeded to run, and unable to keep up, Oscar was almost seen by a couple of Atlas soldiers, but Neo, impersonating Nora, pulled Oscar away and stole the Relic before attempting to stab him. Oscar dodged the attack, but was then swatted aside by Neo, who then escaped.