Laws of Blues Harmonica - 2 Draw

Whether you're improvising or accompanying, if your lick focuses on the 2 draw, you can play it through the IV7 Chord as well and it will sound good (like the A A B Chorus Form for example).

The simple theory is that the 2 draw (referencing a C Harmonica in 2nd Position, Key of G) is G, the Root Note of the I7 Chord. 2 draw is also the 5th of the IV7 Chord, so it works there as well. If your lick also includes the 3 draw, remember to obey the 3 Draw Rule and bend it down to 3' when on the IV7 Chord.