The X-Files/Recap/S01/E16 Young at Heart

Tropes:

 * Its All My Fault - Mulder, regarding the deaths of Barnett's hostage and a fellow FBI agent
 * For Science - Ridley's experiments. The government is interested in his work, but he mostly just seems to enjoy it.
 * Reptiles Are Abhorrent - Ridley uses salamander cells to, giving him a horrifying reptilian hand in the process.
 * Bulletproof Vest - Scully's wearing one when Barnett shoots her. Of course, the audience doesn't know this, so we're supposed to believe she's been fatally wounded.