Star Trek: 10 Times Chief O'Brien Suffered
1. Hard Time
Hard Time is perhaps the ultimate test for Chief O'Brien. The episode sees the man implanted with twenty years' worth of memories, making him believe that he was in a prison cell for that entire time. He both believes it, and knows that it didn't happen - but is forced to deal with the trauma of it.
The story came to Robert Hewitt Wolfe during DS9's first season, but Michael Piller rejected it. It was only when Ira Stephen Behr picked it up for the fourth season that it gained traction. Colm Meaney described this episode as a big acting challenge, as he was forced to play both the man he knew so well, as well as adding decades of despair to that.
The character of Ee'char was added to the original story by Wolfe, who felt that an extra layer was necessary to really hammer home O'Brien's PTSD when he comes home, as the idea of twenty years alone in a cell was, seemingly, not harsh enough.
The end result is a triumph, standing out in an already stellar season of Star Trek. It deals with heavy topics, but handles them gracefully. O'Brien may have had to suffer as much as he did for the show to work - but this episode, along with so many of the others, proved that the old trope - O'Brien Must Suffer - always led the show to higher, darker successes.