If your little sister seems fascinated by the harlequin character in the play you're watching together, it might be because of the brightly colored, diamond-patterned tights he's wearing. A harlequin is a classic comic pantomime character.
In traditional pantomime, a comic performance with silent actors, a harlequin is a funny character who wears a mask and a distinctive diamond-patterned costume. The word harlequin sometimes describes bright, many-colored colored things, like a harlequin circus tent. The oldest versions of the word harlequin — the Middle Dutch hellekijn and the Old French hellequin, reference Hell and mean a kind of demon. In the translation from French to English, the harlequin lost his demonic quality and became a clown.