Fliss was the only member of the five main characters in The Dark Pictures: Man of Medan not to know any of the others to start off, so she definitely was not trusted right away when everything was going on. Everyone quickly realizes she’s on their side though, but that doesn’t mean that can prevent Fliss from getting killed in multiple different ways during the game.
Fliss is relatively safe early on in the game, as even failed QTE sequences that seemingly would have you falling off the boat in the storm have her being saved. The first moment we found where Fliss could die in the game is just like with Brad, but reversed. If Fliss ends up trapped underwater and can’t escape, you as Brad must help her escape by selecting Smash Hinge. This will break her out of the cage filled with water, preventing her from drowning.
Drowning is not the only way Fliss can die related to the water, as soon after she will be grabbed by monsters coming out of the water. Perform all the QTEs here or Fliss will end up getting choked to death in pretty gruesome fashion.
As we already mentioned in both the Alex and Julia guides, there is a moment late in the game where Alex starts to go crazy. Following a QTE sequence with rats, a monster will appear and Alex has the choice to stab himself, the monster, or do nothing. If Fliss was teamed up with Alex here, stabbing the monster will end up killing Fliss as it was a hallucination.