The girl still had clothes on and assisted Hector 3, and later went to the house with him. Does this mean that she didn't encounter Hector 2, and thus Hector 1 never saw her naked through the binoculars?
So shouldn't Hector 1 at least be around in the house as if nothing had happened?
The same thing happened, we just saw it from 3 different perspectives.
The girl's timeline was:
-She's riding along on her bike and sees the car that crashed in the woods.
-She checks on the driver, Hector 2, who brings her deeper into the forest and tells her to strip.
-Hector 1 watches her strip from his lawn chair.
-While Hector 1 is walking up to the road and down into the woods, she escapes from Hector 2, he chases her, and she gets knocked unconscious.
-Hector 2 brings her back to the rock and strips her naked.
-Hector 1 shows up and sees her naked up against the rock, and tries to see if she's alive.
-Hector 2 stabs Hector 1 and chases him away through the forest and up to the scientist house.
-While Hector 2 is chasing Hector 1, the girl wakes up and puts on her clothes.
-The girl goes through the forest and comes across Hector 3 in his crashed van.
-The scream Hector 2 heard after he scared Hector 1 out of the forest was the girl running into Hector 3.
-Hector 2 returns to the rock to find the girl and her clothes all gone.
-The conversation the girl has with Hector 3 acknowledges that she has been in contact with the man with the bandaged head.
-Hector 3 and the girl go to his house, where Hector 3 runs into his wife.
-Hector 3, believing Hector 2 was going to pull his wife off the roof and she'd fall to her death, cuts the girl's hair and puts his wife's coat on her. He tells her to go upstairs to get away from the bandaged man, and she does.
-When Hector 2 is banging on the door, she goes outside, and climbs up on the roof to get away, he grabs her leg, pulls her down, and she falls to her death.
Looking at it from each Hector's perspective, this is how they interacted with her:
Hector 1 saw her naked, went to investigate, got stabbed and chased away by Hector 2 and didn't see her again. He was in the lab at the scientist's house when she was pulled off the roof.
Hector 2 saw her after he crashed, made her strip, chased her down, knocked her out, brought her back to the rock, stripped her naked, chased Hector 1, heard her scream, came back to find her and her clothes gone, then tried to find her in his house to explain things, but ended up pulling her off the roof and killing her.
Hector 3 saw her riding her bike, crashed into Hector 2 and was knocked out, when he woke up the girl ran into him and screamed, she told him there was a house nearby (Hector's) and they might be able to get help there, they went to the house and Hector 3 cut her hair, gave her his wife's coat, and told her to go to the attic. He went outside with his wife and sat in the lawn chairs while Hector 2 pulled her off the roof.