It’s been a couple years since we saw the Kryptonite Kid, that menace from another world who’s evil for apparently no other reason that he enjoys it. In Superboy #99 (July 1962), he returns, and I guess “Kid Mxyzptlk” is not paying attention, because this time Superboy needs to be saved by Pete Ross – who now knows Superboy’s secret identity. The K-Kid then offers to kill Krypto instead of Superboy – to which Superboy agrees, promising to deliver his poor dog for certain doom.
The Kryptonite Kid tries to strand Krypto on a kryptonite-infested world, the dog plays dead, then jumps up and knocks the Kryptonite Kid’s spaceship into a red dust cloud in space. Suddenly the Kryptonite Kid is no longer green, but red – and has no compulsion to be evil.
The now-good natured Kryptonite Kid good-naturedly asks how Krypto was able to survive his attack, to which Superboy splits an invulnerable hair and says he never promised to deliver the real Krypto. He had delivered a Krypto-robot.
Ok, villain defeated and apparently turned into a good guy? Have we seen actual villain recidivism again? No, of course not. Red kryptonite effects are only temporary, you silly.