Mark might not be the cover star in The Dark Pictures Anthology: The Devil in Me, but he definitely has the most plot armor of anyone in the game. There are only a few chances for Mark to die, and they all come at the end of the game. Let’s look at what you need to do to ensure Mark lives. Keep in mind that there will be heavy spoilers below.
How to keep Mark alive in Reunion
Mark’s path is a bit different from everyone else’s because he actually needs more characters to be alive so that he doesn’t run into a situation where he dies no matter what. Basically, you want to avoid having just Mark and Kate alive when you get to Reunion. That means either killing off Kate earlier or keeping either Charlie, Jaime, or Erin (or all three) alive. If you don’t, you’ll be treated to a somewhat secret ending where Du’Met will eventually kill Mark no matter what you do.
How to keep Mark alive in Lake
If you don’t run into Du’Met’s final deal, Mark will have quite a few chances to die in the final scene. You need to pass all of Mark’s QTEs and also have Kate (or Jaime if Kate died earlier) help him instead of jumping off the boat. Then, when Du’Met is dealt with, you’ll need to pass one more QTE to jump off the boat with Kate (or Jaime), and he’ll make it through the entire ordeal.