Say we have this sequence C-D-C-D. That is a I-II-I-II progression in C Lydian.
I'd like to hear your opinion about the subtonic VII chord - as bVII - profusely used in rock/pop music.
Your example of C - D would be one of those uses: C as bVII and D as I.
That chord progression/motion has its name,
Subtonic shuttle (from Mixolydian schemas): I–♭VII or ♭VII–I.
Let's take Michael Jackson’s “Wanna Be Startin’ Somethin."
It's in
E major.
We have that D major chord
borrowed from E minor - the parallel minor E major.
The song has a two-chord repetitive loop:
D - E
or with the bass-line,
D/E and E.
Let's say, a guitar player needs to play some "improvisation" over those chords.
And the guitar player thinks,
"It's easy.
We have a simple
IV - V progression,"
but the bass player says, "No it's not IV - V progression.
It's the
Lydian shuttle I–II♯."
Suddenly, an educated piano/keyboard player says, "No, you are wrong.
It's the
Subtonic shuttle bVII - I."
Now, the guitarist says, "Hey, you are confusing me.
What MODE should I use to play over those D and E chords? What "
other notes" could I play?"
What would you tell the guitar player?