Pain Bot

"Pain. Pain. All I know is pain."

- Pain Bot's only quote

The Pain Bot, also known as Little Buddy by Cyborg, is a sentient, mobile torture machine created by Brother Blood and utilized to battle/interrogate the Teen Titans. It is a minor antagonist in Teen Titans Go!.

Waffles
The Pain Bot makes its first appearances in Waffles. When Brother Blood wants the Titan's voice code to unlock their armory, he plans to endlessly torture them with the newly constructed Pain Bot. Though Robin, Raven, and Starfire give in, Beast Boy and Cyborg refuse to do so simply because they're playing a game where they can only say "Waffles". This leads to excruciating torture until Brother Blood is too annoyed to continue and forfeits.

Little Buddy
Later, Blood still utilizes his torture machine to not interrogate the Titans, but battle. After he is defeated, Pain Bot is rendered docile and harmless since no one malevolent is in control of him. Despite the Titans' veto against it, Cyborg secretly attempts to make Pain Bot his "pet". During this, the Pain Bot constantly tries to brutally murder the Teen Titans when their backs are turned, but is stopped by Cyborg. Despite Pain Bot's sociopathic and sadistic programming, he and Cyborg manage to form a secret bond that is eventually revealed. Though the Titans think Pain Bot can be cute, his violent and murderous outbursts are too much to handle and he is cast out of the tower.

They manage to organize a tournament deciding whether or not Pain Bot can stay by having fight with the Titans' pets, including Robin's bird, stick, boombox, and sentient birdarang, Beast Boy's wolf, and Raven's demon. Thanks to the endless amounts of Pain Bot's fighting utensils, he either beats or kills them all. However, he is defeated by Starfire's supposedly calm pet, Silkie, when he was eaten.