Who pays an Ally's Cost of Living?

[thom]

In a Fantasy [non DF] campaign, is a Player Character presumed to cover his Ally's daily and monthly COL out of the player's funds/treasure share?

I ask because it's about to come up in my game...I'm taking the point of view that an Ally doesn't get a regular paycheck from his PC (as compared to a hireling); so it would make sense that the PC has to pay the COL for his Ally.

Does that make sense? Or is there a better way I'm missing. Just to clarify, I am requiring my PCs to pay their COL out of their earnings from investments or adventuring...