If you read the book, you would know the answer.
Sam and Eric are frightened when they are tending the fire because they mistake a dead pilot's parachute for a monster. The darkness and their imagination play tricks on their minds, creating a sense of fear and panic.
sam and Eric
In Chapter 6 of "Lord of the Flies," Sam and Eric are frightened while tending the fire because they see what they believe is the beast in the woods. The nightmarish sight, amplified by their tiredness and the darkness, makes them question their safety and sanity, heightening their fear. This encounter challenges their sense of security on the island and deepens the boys' fears about the unknown threats lurking around them.
In "Lord of the Flies," it is Simon who is tending the fire when the boys' fear of the beast emerges. As the boys mistake a dead paratrooper for the beast and flee, Simon remains at the scene and discovers the truth about the figure on the mountain.
Sam and Eric describe the beast as a "snake-thing" or a "beastie" that they saw while tending the fire on the mountain. They are uncertain of its true form, but they convey their fear and belief in its existence to the rest of the boys.
In the beginning of chapter 10 in "Lord of the Flies," Sam and Eric were tending to the signal fire on the mountain. They were responsible for keeping the fire burning so that passing ships or planes might see the smoke and rescue them.
It is never explicitly stated in Lord of the Flies where any of the boys are from. Jack does say, "We're English." Ralph also remembers living in a cottage in Devon, England but there is no specific mention of where the twins came from.
The fire was dying out
Sam and Eric, Piggy, and Ralph.
Sam and Eric mistake the dead parachutist for the "Beast" due to the way the parachute moves in the wind and the terrifying sight of the body. They are so frightened that they run back to the group and report seeing the Beast on the mountain.
getting fire wood
Sam and Eric. SAMNERIC