Toothache Simile
Although things between the boys have been copacetic for a while, seeing the threatening letter from Edmund re-ignites Charles' fear and sense of dread, which is said to "dart through him like a fresh toothache." This simile is appropriate because the fear he is feeling has not been a constant. Toothache is a pain that comes on suddenly, in fits and darts of sharpness, when something is eaten, for example, or a beverage is too cold. The fear that re-awakens in Charles is just like this, coming on again suddenly because it has been triggered by the letters.
Thunderstorm Simile
Charles likens the temporary nature of his power over Edmund to a thunderstorm, in that it is extreme and intense whilst it is going on but it eventually dies down, and afterwards everythng in the woods returns to the way it was before. This is what would happen in his life.
King of the Castle Metaphor
The author uses the phrase "King of the Castle" as a metaphor that identifies the way in which Edmund considers himself, and to explain the competitive nature of the boys' relationship from the very beginning. Being the young man of the house was not a role that Edmund considered could be shared and so he determined that he would be the king of the castle and have more rights to call it home than Charles would. The most important child in the house is likened to the king because in the days of castles, the king was the most powerful person in the land and the one who made all the decisions. This is the role that Edmund sees for himself.
Raw Meat Simile
The cowman at the farm is said to have hands "like raw red meat". This is something that is frightening to the boys, and it also reflects the nature of his work, which is very manual and also done in all weathers and conditions. His hands are chafed by the weather and also scarred by the work that he does. Having raw, red hands conjures up an image of someone with blood on their hands also which suggests a threat, something that Charles is seeing in his general surroundings.
Pale Face Simile
Edmund's face is said to be "as pale as his limbs" which suggests an unnaturally white hue. Typically a child's face would be pink, or at least flushed with the redness of having run around. In a cold climate such at theirs, the face would typically be darker than the limbs which would be covered for most of the year. The fact that his face is as pale as his limbs suggests something that is rather deathly, and unnatural, and adds to the threatening nature of Edmund from Charles' perspective.
