Oceanhai

young Poison Ivy zapped by a mutant; ages up to young adult body with child mind

Jerome "not the Joker" Valeska dies multiple times. Real deaths, not fake ones.

Famed assassin Victor Zsasz skips out on a shootout to go get milkshakes.

The Mad Hatter dies and is brought back by Magic Green Water™.

Jerome takes over a carnival; gets his face punched off.

The Penguin falls in canon gay love with the Riddler; neither handles it well.

Poison Ivy ODs on magic potions; stuck in plant cocoon; ages up to new actress

Surprise! Jerome has a secret twin brother and he's WORSE.

Babs's arc: love interest -> crazy killer -> mob boss -> cult leader -> realtor

Oswald's Cinderella arc that ends with cannibalism.

Ed kills his girlfriend, then meets an identical one; this is never explained.