10 Best Riker Episodes In Star Trek
8. Second Chances
There, but for the grace of God, go I. In a classic episode of Riker against Riker, this sixth season offering gave Frakes a chance to play against himself as Thomas Riker, his transporter clone, is introduced. This is a nice take on the surprise twin trope. Thomas isn't an evil genius and he's not the mad wife hidden in the attic. He was simply an unlucky version of the man we'd spent five years getting to know, lost because his life took another direction.
To be clear - Frakes is playing the same character in all scenes, the only difference being experience. This version of Riker never rose through the ranks to Commander. He never fell out of love with Troi. He thankfully still has the beard, although his re-introduction in Deep Space Nine's Defiant would see him lose the mutton chops.
The Next Generation never did a mirror universe episode, with the possible exception of Yesterday's Enterprise. While Thomas Riker is not Will's polar opposite, he is something of a throwback - he is a man who has spent years in isolation, ruminating on the chances that brought him to where they find him. It is telling that he is ready to sacrifice to himself by the end, believing he can never have the life that he sees Will living.
It is that very difference that he is left with on his return to the real world and though his path would lead him to darker places, he brought with him the knowledge of a beloved first officer, stepping onto a different path.