How about Mercenaries?

I think they did something similiar, to a very minor extent, when they added Golems.

I would like mercenaries being added to PoE, maybe limited to a single one at a time.

But it would be cool even if they just expanded the golems concept by adding more customizability (for example, every few levels at gem level up you are asked to pick between a couple of different abilities).

I hope they don't. D2's mercs were just a way to get outrageous mana regen or some other aura that you didn't have to pay the associated costs for. D3's were just there for their monologs. I don't see them adding much to the game without a huge re-eval of our current game.

I would personally enjoy it for solo parties only; however, they should be limited in certain areas. For instance if you could gear them like an aura bot why would anyone bring anything but that? I'd say no aura stacking, could only be used in solo parties (which should also increase the difficulty as if 2 people were playing), and to be unusable in SSFL's.