Campfire

The Campfire is where all the campers at Camp Half-Blood gather around, near 8:00 p.m., to sing campfire songs, before reporting to their respective parent's cabins. The campfire is known to change colors on the campers' moods. The Apollo Cabin mainly leads campfire songs such as one song mentioned where they sing how their grandmother dresses for war, pointing at different body parts for the different pieces of armor. The campers sacrifice a portion of their food into the fire for the Greek gods.

Magical Properties
The campfire has some magical properties. The height and the color of the flames depends on the general mood of the campers. If the campers feel really excited or happy the campfire will rise over twenty feet high and turn golden. But if the campers feel grim, upset, or anxious the fire will turn into a deep shade of purple or black.

The Lightning Thief
When Percy first arrived at Camp Half-Blood when he is at the campfire, he sees a little girl tending the fire but nobody notices her. When Percy returned from his quest, the Ares Cabin showed him a burial shroud they had made for him in the event that he died. However, because he made it back safely they burned it in the campfire (something Percy enjoyed doing). Percy and the other campers passed around s'mores while the Apollo campers lead the sing-along.

The Sea of Monsters
After winning the chariot race, Clarisse LaRue is awarded a golden laurel at the campfire which raises everyone's spirits and in turn caused the flame to grow. When Percy told everyone he knew of a way to save the camp, everyone was quiet, but the flame showed that they were all interested. However, Tantalus gave the quest to Clarisse instead of Percy, which a lot of campers thought was unfair and the campfire greatly diminished as people started leaving.

The Last Olympian
After the campers burn Beckendorf's shroud, Percy stays and watches the flames. He notes that the fire is burning black. This signifies that the campers moods are at their lowest point ever throughout the series.

The Lost Hero
During the campfire Rachel talks about the Prophecy of Seven and begins repeating it when Jason interrupts her and finishes it in Latin. She also says that she feels that some of those in the prophecy are there tonight. She also is taken over by the spirit of the Oracle and gives another prophecy for a quest. Drew charmspeaks everyone at the campfire to convince the campers that she should be on the Quest for Hera but she is out spoken by Piper who can also charmspeak. Later Jason proved himself to be a son of Zeus (actually Jupiter) by summoning a lightning bolt to hit the campfire, putting it out.

The Lightning Thief
Hades takes form in the fire and demands to see Percy Jackson. When he is refused he begins attacking the campers and tells Percy that he has his mother. He demands for the Master Bolt in exchange for her. Then Percy reconsiders.

Trivia

 * There were only two known times the campfire was a deep shade of purple. When Tantalus was in charge instead of Chiron. Also, it was mentioned in The Lost Hero when Chiron was talking about Percy's disappearance and Jason's quest.