YMMV / Star Trek: The Next Generation S7E10 "Parallels"

• Nightmare Fuel: The Riker from the Borg-overrun universe is a terrifying sight, where he's given in to despair and is willing to allow the universes to all get crushed together to avoid going back. More than a few of the novels have had Worf haunted by seeing this, and how close his own universe could have come to it.
• Spiritual Successor The Star Trek: Voyager novel "Echoes" combined this episode's premise with Voyager's own "Deadlock", and made the idea epic-scale, plus Darker and Edgier. More on the episode's YMMV page.