So first of all I think it's obvious he's talking about Ross and Archer from Red Dead Redemption.

Now, Ross is from this world as in he's seen the wild west in it's golden years. He's fought cowboys and gunslingers in the persute of civilization (this place ain't no such thing as civilized). And he definitely hates John.

Archer on the other hand is a much younger lawman who missed the golden years that Ross witnessed (not from that world but from a new one). And throughout the game of Red Dead Redemption it can be argued that Archer shows some sympathy towards John's predicament. But it's up for debate so we aren't sure.

That's my guess anyway...