1) Snookie - Act 1 Rogue (Fire Archer)
She spreads the burning situation with everything she encounters. Hence, the fire.
2) Mike "The Situation" - Act 2 Combat (Prayer Aura)
The dude is a team player. He is always willing to take on a grenade for the night for his boys. Hence, the prayer aura.
3) Ronnie - Act 5 Barbarian
He's just a big dude. Hence, the Barb.
Disclaimer: I don't care about effectiveness throughout the WT. The chosen merc is mostly for entertainment purposes for me. I'll make sure all three choices are loaded up gear-wise so that they will all be effective and supportive towards DJ Pally (Pauli) D, the Fist Pumper (FOHer).