Marek

Marek Curtis Wright (Ingame Marek) is a character in the quest Sea Exploration. He is one of the three mercenaries hired by Junior to protect him on his journey through the uncharted seas. You give him an Adamant longsword at the beginning of the quest. During the quest, he helps fight off the pirates by engaging one in the background. He is the only one of the three to actually kill his target, as the cutscene shows.

After the quest he, Steve, and Junior can all be found wandering around the ship. If you speak to him after the quest you get the following dialog.
 * Player: Marek! How have you been?
 * Marek: I've been pretty good latey. With the money from Junior's expedition I'm thinking of retiring back to Varrock.
 * Player: Oh? What do you plan to do there?
 * Marek: I think I might be able to buy my way into a Knighthood. I hear the crown's a little short of cash.
 * Player: Ha ha, good luck there Marek.
 * Marek: You too, Player.

After starting Peril of the Three Kingdoms, Marek seems to have moved from the boat to Varrock Palace on the Third Floor, now titled "Sir Marek", and he appears to be a well dressed nobleman.