Unlike most KX-series droids who are effectively emotionless, K-2SO's reprogramming led to the development of a fully self-aware personality. He is cynical, blunt and does not hold back his opinions, but he is well-meaning and honest. He is also prone to sarcasm and stoic, often mentioning that he has calculated the poor odds of success in any given situation (which Cassian Andor then refuses to hear). His sarcasm extends to the point where he disobeys minor orders and proves his ability in given missions, as seen on Jedha. K-2SO is fairly independent and frequently disobeys orders he feels are counterproductive, scolding his organic compatriots for ignoring his advice. He genuinely regards Cassian as a friend, and is selfless to the point that he feels no hesitation in sacrificing himself in order to protect him and Jyn Erso during their mission to steal the Death Star plans.
Powers and Abilities
Droid Strength: As a droid, K-2SO is physically stronger than most other sentient beings.
Droid Durability: As a droid, K-2SO can take far more damage than most other sentient beings.
Master Analyst:' Despite not being an analyst droid, K-2SO can estimate if his allies' tactical strategies were 97% or 100% effective. It is likely that he was programmed with this feature by the Rebel Alliance.
K-2S0 first appears to rescue Jyn Erso from an Imperial labor camp on Wobani. He accompanies Cassian and Jyn to find Saw Gerrera on Jedha, who had been close to Jyn's father Galen.
On Jedha he is told to stay with the ship, but later reappears to help Jyn and Cassian to fight off Stormtroopers after Saw Gerrera's henchmen make an attack on an Imperial cargo transport. He later helps them out of Jedha.
On Eadu he is told to stay with the ship, which he does. He later agrees to accompany Jyn to obtain the Death Star plans, and on Scarif imperial base he communicates to Cassian and Jyn the location of the Death Star plans in the control room. Jyn gives him her blaster before attempting to steal the Death Star plans. He tries to fend off attacking Stormtroopers but eventually succumbs due to multiple shots from them.