My band has a former member who played with us for a few years. The music was written entirely by another member of the band, though this former member did apply his own "personal style" to the playing of it. He also plays on the recording, though that was his only contribution towards the album itself, financially or otherwise.
There was no formal agreement signed, and no verbal arrangements made. What is a fair compensation? Does he still get an equal share of profits from the album?