Bass Fills With C# Mixolydian
Where C# Mixolydian lies on Bass's fretboard, and the fill it feeds.
C# Mixolydian runs 7 notes to the octave. Below it is laid onto this chair's EADG fretboard with every C# marked, because what a fill needs mid-song is not the pattern — it is where the root is when the chord changes under it.
Major with a flatted 7th (b7) — bright and bluesy. The dominant chord turned into a tonal center with a rock/folk edge.
Heard in: "Sweet Home Chicago", "Norwegian Wood" (Beatles), Celtic and folk music — anywhere a major sound needs a darker, looser edge.
The bass rarely takes a fill, and that is precisely why these matter: the notes between one root and the next come out of the scale, and a walk that lands wrong is the loudest mistake in the mix.
Play it slowly against the audio until the shape stops being a shape, then take it to a song in C# and let the melody pick its own notes out of it.