Spare and lighthearted, Rats was inspired by the personal hand of the illustrator Scott Nash. Its small body height and tall ascenders support an oldstyle spirit drawn from early second-century Roman cursive scripts.

Rats was designed by Jean Evans, who was assisted in the digitization by Jill Pichotta. The character set is supported by a whimsical set of dingbats which include starbursts, clouds, and zig zag arrows.