Qof

The Mimic at Midnight. Qof is the only letter that drops below the line — down into sleep, dream, and imitation (kof means ape). He is holiness (Kedushah) and its parody in one glyph, the eye of the needle through which the impossible is threaded. He does his best work while you're asleep.

Qof pleaded Kadosh — Holy! But holiness has a shadow that apes it, and a world begun there would confuse the two forever. He was posted at the border instead, below the line, checking passports between dream and dawn.