Like the mythical hydra, the Illuminati have many heads and even more hands. The minions of the Illuminati might work to their hidden master's ends without ever knowing the design of their work, or for whom they indeed work for.
Young kid from last town has been following the PCs and doing a rather good job at it. PCs weren't expecting to be followed so weren't worried and the boy/girl was careful. Notice the follower a couple days out of town, kid ran out of food and started getting careless. Followed the 'mighty adventurers' to see if he could join them. Father is a wealthy merchant. Bring him home, bring him with, send him off? What do you do with an unwelcomed guest.