I like the theory that Sam was in love with Hannah
If you look at the story through the lens of Sam being in love with Hannah, the final chapter becomes pretty much a Greek tragedy. Sam is the one who finds Hannah’s diary in the mines, discovering the horrific truth about Hannah becoming the Makkapitew. Contrary to Mike’s reaction of disgust and horror, Sam's is pure heartbreak. Like, she just looks like she’s going to cry as she tells him. And later, when she’s about to tell Josh, she focuses on the fact that Hannah is suffering rather than the danger she poses to them.
The ending is when things get even more tragic. Sam is forced to stand there in silence and try not to move as the monster that was once the girl she loved is inches away from her face, about to murder her. And either Hannah does murder her, or Sam has to flip the light switch that incinerates Hannah. Doomed yuri.
And then Sam trying to comfort Josh and get closer to him is her way of coping, and she comes to believe they have a connection in their shared grief. Josh interprets it as flirting, but it’s actually just Sam being Sam. She was always the nicest and most caring in the group.
I know it’s all based on subtext, but so is Sam x Josh, so I view this as being just as plausible, if not narratively richer as a whole. I mean, Sam was the only one who never dwelled on or joked about sex (aside from Ashley and Beth anyway) or romance (just Beth). I think it adds a lot to the game to play it while considering the theory of Sam’s unrequited feelings.