Leech

To leech means to join a party or enter a mission and then do nothing. Leeching commonly refers to a deliberate act of malicious intent, but even a person who joins a party to complete a mission/quest and goes AFK is still leeching on the rest of the party.

In addition to the dishonesty involved in reaping the rewards of other people's work and not helping, leechers hurt the party in many ways: Leeching is a common problem in Competitive Missions such as Fort Aspenwood, and in Alliance Battles. It is commonly automated through the use of bots. Bots that leech should always be reported.
 * The party is missing a player, who, if they do nothing else, will help absorb some of the enemy's firepower.
 * The party may have expected this player to perform a specific role needed for the completion of the mission.
 * Often, people will be discouraged by the presence of leechers and be tempted to leave.
 * It can also deprive the team of experience.
 * When someone is AFK at the spawn, and the rest of the party is defeated, it stops them from respawning, or returning to the outpost to try again, thus disintegrating the party (which for most things like the Fissure of Woe take quite some time to form a group.)