Are there different grammatical rules for lyrics as opposed to prose?
Oh, I don't think there are really any grammatical rules for writing lyrics, or we wouldn't have such fine songs as "Is You Is Or Is You Ain't My Baby?" and many others along those lines. I quoted one E.Y. Harburg lyric in the "songs about spring" thread yesterday that is--deliberately--a grammatical train wreck, but a delightful lyric all the same. It all depends on the character who's supposed to be singing.