"My name isn't Frisk! It's Chara! AND YOU'RE IN MY WAY!!"
– Chara as they charge towards Frisk's friends.
Chara is the main antagonist of Swaptale. They are the adopted child of Asgore and Toriel and the adopted sibling of Asriel. They are possessing Frisk from the Genocide Route.
Calling him by his real name, they demand to know where Sans was and what Flowey did to their Fight button. They accuse him of messing with the timeline and tell him that he can't have Determination. Flowey escapes and Chara calls after them still demanding the whereabouts of Sans. The Sans from Frisk's timeline appears behind Chara, who upon turning around is shocked to see all of Frisk's friends, alive and unharmed.
Tortured by flashbacks of their victims, Chara charges at them, but is stopped by Sans, who recognizes that they are the one from his nightmares and attacks them with psychokinesis until he is stopped by Toriel, still think they were Frisk. Toriel comforts them, asking where they learnt the name Chara. Chara, conflicted by Frisk's sympathy for their murders, apologies while attempting to kill Toriel.
Sans uses his psychokinesis to stop them, only to be accidentally killed by Toriel, causing Chara to be released. Undyne grabs them by their shirt and scolds them for their cruelty and telling them they're not worth Sans.
Chara's conflict worsens and they forcibly break Undyne's grasp on them and falls to the ground, crying and shouting that they don't care and that they'll kill them all, with Frisk almost completely losing their sanity to Chara's evil influence.