John Trelawney, a wealthy landowner, finances the expedition to Treasure Island after Jim Hawkins and Dr. Livesey bring him Captain Flint's treasure map. He commissions the schooner *Hispaniola* and oversees crew recruitment. His gullibility leads to Long John Silver deceiving him, resulting in the hiring of mutinous pirates.

Trelawney bursts with a bombastic and excitable personality, often displaying childlike enthusiasm for pirate lore and treasure hunting. Despite explicit warnings from Dr. Livesey, he struggles to keep the voyage's objective secret, inadvertently revealing critical details about the map and destination to the pirates. His initial overconfidence causes him to dismiss Captain Smollett's concerns about the crew.

Tall (over six feet) and broad, Trelawney has a roughened, reddened face from prior travels and prominent black eyebrows that signal a quick temper.

Following the crew's mutiny, Trelawney admits his mistake to Captain Smollett with humility. During the island conflict, he demonstrates leadership by coordinating loyal crew members to overpower pirates left aboard the *Hispaniola*. He later joins Livesey and Jim in a fortified stockade, where his marksmanship proves exceptional, including a noted long-range shot from an unstable boat that nearly kills a pirate gunner.

Trelawney forms a strong emotional attachment to his companions and openly grieves the death of his gamekeeper, Tom Redruth. After securing and dividing the treasure among the survivors, he returns to England with the remaining loyal crew.