Mxyzptlk

Mxyzptlk had just returned to Earth from the Fifth Dimension. He remembered his time pretending to be principal of Stanhope Boarding School where he met Lana Luthor and Kara Zor-El (Supergirl).

He tracked down Supergirl. He really wanted to fuck with her and slowly turn her life into a living hell of humiliations using his reality warping abilities.

He found Supergirl helping to rescue people from an apartment building on fire.

"That's the last of them," said Supergirl as she gently landed with an elderly man in her arms. There is no one else in the building, and I made sure the gas lines were sealed."

"Thank you, Supergirl," said the fire captain.

Supergirl stood on the street with her fists on her hips, striking a heroic pose.

Mxyzptlk smiled as he watched, perched atop the building across the street from the fire.