is known about Sarah’s personality while she was alive, but she maintained a seemingly stable friendship with Luther and the Fun Gang. However, she was stated to have a habit of walking all over her friends, suggesting she was likely inconsiderate, overbearing, and somewhat arrogant.

After her death, upon realizing that her friends had covered up the circumstances surrounding it, Sarah descended into madness and obsessively vowed revenge. Consumed by animosity and hatred, she was driven insane, embarking on a killing spree thirty years later to exact her vengeance. Sarah's sole focus was to inflict endless suffering on her friends, trapping them in a virtual world where they would endure the torment she experienced for three decades. Her unrelenting rage led her to target Luther's son as an act of spite. Her anger was not only rooted in her own death but also in the impact it had on her family, particularly her girlfriend, Lily. She expressed this to Luther before killing him and dragging his soul into her digital realm, resenting that her friends had moved on and built families while her own family suffered.

Sarah ruled her virtual world with an iron fist, developing a god complex. Initially viewing the game as a void to torture her friends, years of sadism further corrupted her already fragile psyche, making her mad with power, sadistic, callous, and psychotic. Despite having the power to move on to the afterlife, she chose to stay in the cursed game, reveling in the control and the torment she could inflict. Her arrogance, vanity, and egocentrism were apparent as she looked down on others, proclaiming them as mere inhabitants of "her world."

Sarah was a massive control freak who governed with tyrannical authority. She viewed herself as the ultimate ruler, boasting about her dominion over the game's inhabitants. Her controlling nature was matched by her manipulative tendencies. She could easily create a facade of wanting to reconcile, emotionally manipulating her friends into believing she forgave them before revealing her true intentions and delivering a lethal blow. When she lost control, she would break down and practically throw tantrums. At one point, she even attempted to delete the souls within the game after failing to regain control, showing that she preferred her victims dead rather than free from her dominance. Witnessing even the slightest resistance from Luther was enough to provoke a violent, glitch-ridden rage, highlighting the extent of her instability and need for absolute control.

Her madness drove her to extreme actions, showcasing her sadistic pleasure in inflicting pain and suffering. Sarah’s psychotic behavior was evident in her enjoyment of the power she wielded and the sadistic glee she took in torturing her friends. Despite having moments where she could potentially move on, Sarah's love for control and torment kept her tethered to the cursed game, demonstrating a deeply disturbed mind corrupted by years of unchecked power and rage.

Despite her monstrous actions, Sarah's descent into madness was triggered by her untimely death in an unintentional accident. Her vow for justice was driven by the trauma and anger over her fate and the suffering it caused her family. However, her actions, particularly her continuation of violence after exacting revenge, were far worse than the initial deed, as Luther pointed out. Sarah justified her crusade as "doing what was right," yet she inflicted the same pain on her victims and even threatened their loved ones unless they confessed. Her killing of Kyle and attempted murder of Tom, who were innocent and merely investigating the haunted game, further highlighted her hypocritical and sadistic nature. Although she briefly regretted killing Kyle, her need for control and justification quickly overshadowed any empathy. She openly admitted to enjoying the suffering of her ex-friends, driven by sadism and petty revenge rather than justice.

Despite her egotism and desire for sadistic entertainment, Sarah remained a victim of her tragic death. The isolation and torment in the void led to a further mental collapse, blinding her with rage and fear of being forgotten. Manipulated by an unknown entity, Sarah became easier to influence, although moments of genuine remorse occasionally broke through, especially after killing Kyle. Her humanity lingered, as shown by Luther's near-success in redeeming her, which was thwarted by the entity's intervention. Throughout her ordeal, Sarah continued to show genuine love for her then-girlfriend Lily, who was among the first she thought of upon awakening in the void.

Appearance Like most Sonic.exe incarnations, Needlemouse manifests as a corrupted sprite of Sonic the Hedgehog, often in horrifyingly supernatural ways. In Needlemouse's case, she appears with a more purple or pink hue to Sonic's usually blue fur, likely reflecting the color of Sarah's sweater, while Sonic's white gloves usually end up with a yellow or orange tone, and the peachy skin tone becomes much paler. Supernatural corruptions of the sprite include turning Sonic's eyes into larger, red irises in black sclerae, usually alongside a gaping pitch-black mouth, occasionally with visible bloody teeth. Also, despite her spirit evidently inhabiting the Classic era Sonic games on the Sega Genesis, her Sonic form is taller and lankier as per his Modern era design, as opposed to the shorter and stouter Classic design. Needlem0use's perpetual smile is also either a closed smirk or a gaping Duchene grin, obviously meant to be threatening as she is described as constantly angry, although the smiles could be glee at the prospect of torturing her former friends for killing her.

Sarah, the true form of Needlemouse, often manifests as her human form, usually one resembling her from at the time of her death and lacking any supernatural changes, with the exception of red irises. Sarah is a 24-year-old young Asian woman of average height yet voluptuous build. She wears a purple sweater with a lighter-shade stripe running across the chest and upper arms and the hem of the sleeves, dark blue pants fastened with a brown belt with a yellow buckle, and white socks with dark spots around the toes and heels. Her raven-colored hair is long and wavy, and her skin tone is pale (although she had relatively tan skin when alive, becoming paler in death). Supernatural corruptions of her human form often include profuse bleeding from her eyes, mouth and forehead/scalp, and turning her skin pitch-black leaving only wide-blank eyes and teeth. She can also manifest a much more demonic and ghostly form, appearing more akin to a bloated, rotting corpse with decaying skin.

Both Needlemouse/Sarah's forms are almost always seen with unnerving big smirks and blank stares, giving her a possessed or deranged expression. It's also been described these grins are meant to mask or express her immense undying hatred and anger of her former friends, as she keeps smiling widely even when lecturing them with an obvious hateful scathing inflection.