Lord Stanley, Earl of Derby, is Richmond's stepdad. Because of Stanley's relationship to Richmond (who eventually takes Richard's throne and becomes King Henry VII), King Richard tries to keep a close eye on him. But that doesn't stop Lord Stanley from secretly helping out his stepson. In the middle of the play, Lord Stanley has a dream about a boar knocking his helmet off his head, which seems to symbolize Stanley's fear that Richard will kill him (3.2.5). Check out "Symbolism, Imagery, Allegory" for more on this.