Pour backgrounds have an unpredictable nature, so even with the same colors, no two will be the same. The finished pour will be unique, and cannot be precisely controlled. What I can do is work with 2 or 3 main colors, and we'll see what we get! Then in the portrait, I'll use an additional highlight color and shadow color, and sometimes an additional medium-range color that compliments the background well.
If you don't know what colors you'd like, we can decide that later, too.