Chords in B Aeolian

B Aeolian is built from the notes B, C#, D, E, F#, G and A. Its scale carries 2 sharps. Harmonising that scale in thirds gives seven chords — 3 majors, 3 minors and 1 diminished — starting on Bm as the i. The chord on the fifth degree is F#m rather than a major V, so B Aeolian has no leading tone and resolves by step and colour instead of by dominant pull — the sound that separates it from a plain B major.

Beyond those seven, B Aeolian commonly borrows B (I), C#m (ii), D#m (iii), E (IV) and F# (V) from the parallel major — the mixture chords that give a progression somewhere unexpected to go.