勾 gōu to hook

to hook; to join; to connect; to entice; to tick; to collude

How it came to be

The character is another way of writing the sentence sign, with the mouth inside it changed into a different shape.

To hook/link, and by extension to entice or scheme: 勾住 (gōuzhù) to hook onto, 勾勒 (gōulè) to outline, 勾结 (gōujié) to collude, 勾引 (gōuyǐn) to seduce.
Also to tick/cross out: 勾选 (gōuxuǎn) to check a box, 一笔勾销 (yìbǐ-gōuxiāo) to cancel/write off in one stroke.
Many senses radiate from the hook: linking, ticking, and luring someone in.