10 Most Shocking Plot Twists In Star Trek: Voyager
5. Latent Image
The Doctor being an EMH provided plenty of plot points for the Voyager writers and this episode is arguably one of the best that centre on him.
After discovering evidence of a surgery he doesn't remember performing on Harry, the Doctor begins to suspect he has been subject to sabotage. This leads both him and the audience to believe there is a malevolent presence aboard the ship determined to ensure he doesn't remember. Both the EMH and the audience are left completely shocked when it is revealed to be Janeway.
The story then unravels and it is learned the Doctor had to make a tough decision and that decision caused him to have a meltdown (or the holographic equivalent of one if you will), and the crew decided to erase the memories.
The complete subversion of expectations around who the saboteur was and why it happened provided an excellent plot that has gone down as one of Voyager's best episodes. Up until the reason Janeway explains why the memories were erased, viewers are questioning whether this is the real Janeway or if she was under an alien influence.
The revelation that the Doctor is able to have a mental breakdown of sorts is something that is never discussed again, which is odd considering how important this episode is in the Doctor's character development. There are no consequences outside of the episode for what has occurred, which is an issue with the episode.