Mengsk a master or a puppet?

Mengsk doesn't care whether he is a puppet or not, so long as he has power. Because of that, it is difficult to say whether or not he is a puppet.

 

Mengsk can't be a puppet since right now he's the most powerful Terran in the sector. He's the tyrant of the Dominion with no Terrans having the power to oppose him in the entire sector, aside from Raynor's Raiders, if even that. The Combine and the Protectorate don't match up to the Dominion in resources and military to be able to be a serious challenge to his power. I also doubt he's under control by some Protoss since he apparently loathes them. It's possible he's under a mind control, but it seems unlikely given his attitude toward the Protoss. As for being infested, that's out of the question. His ghosts and scientists would've found out at once if he was infested.

 

Astute observation. JUST like Kerrigan, Mengsk is nothing more than a traitor to his own kind! =)