SPOILERS AHEAD
YEAHHH TRIUMPH AT LAST!!! Great job beating the game, hope you've had fun so far! Despite the anguish the skinwalker gave you, anyway. If you got the "good" ending, the other two do have to do with Fern and then something else that will come up (not the windows, but good guess). If you got others let me know how much of a hint you want! (Like if you still want to be able to discover it for yourself, or if you want me to just tell you.) To get the other endings you will have to go through the chase again-I recommend turning "Always Dash on" in the options menu for that, it'll make you run automatically. And slightly to the left and down in the corn maze is the best route.
Thanks again for your comments, looking forward to seeing what you think of the other endings and your review!