Prophet of Mercy

The High Prophet of Mercy was one of three Hierarchs that lead the Covenant High Council. He was by far the oldest. His birth name is Hod Rumnt.

Biography
He served as the Philologist on the Forerunner Dreadnought, where he led the priests prior to his ascension to Hierarch. He became the third Hierarch after the Oracle of the Dreadnought attempted to launch the Dreadnought, during which time it referred to the humans as his creators. His tenure has been marked by several tense debates with Elite High Councilors over the proper dispensation of Forerunner artifacts. Mercy is considered one of the last of the old guard of the Prophets - a hard-liner who publicly questioned the wisdom of the Prophets' demilitarization at the end of the Prophet-Elite War.

Being the oldest member of the Prophet triumvirate, Mercy is well-acquainted with the Covenant's governmental systems and history. During a meeting with Thel 'Vadamee and the Prophet of Truth, he mentions a bit of Covenant history, citing the Grunt Rebellion and the Taming of the Hunters.

He stayed by Truth's side after the death of the Prophet of Regret, and seemed to be more of an adviser or supporter of Truth than an equal. As the Covenant Civil War began, Mercy still supported Truth's actions, even as it seemed that Truth was unraveling the very foundations of the Covenant.

He and the High Prophet of Truth were attacked by Flood Infection Forms on High Charity. As they prepared to depart for Earth with the Forerunner Dreadnought to begin the Great Journey, a single Infection Form made it past the Honor Guard Brutes, and latched onto his neck, and devoured his windpipe. Even as Tartarus attempted to save him, Truth intervened and let Mercy die, saying "The Great Journey waits for no one, brother. Not even you." Before his death, he was found by the Master Chief, who questioned where Truth was going. He answered, "Earth, to finish what was started. And this time, none of you will be left behind." The Master Chief then violently tore the infection form off Mercy's neck, killing the old Prophet instantly but saving him from being infected by the Flood.

Personality
Little is known about this Hierarch. However, Mercy can be seen as passionate and knowledgeable, as seen in the cutscene before the level Sacred Icon where he shows his excitement about Halo, expressing hope that the Great Journey should begin very soon. It's very possible that he has a sense of propriety, seeing that he talked Truth out of condemning Regret, as described on the level Regret, but that doesn't necessarily mean he's merciful. He is perceptible and an authority on the Forerunners and their knowledge, he can be considered the Prophet of Truth's right-hand. Without Mercy to advise him later, Truth becomes much more irrational and aggressive in Halo 3, even toward his subordinates (very much like Regret was before the Great Schism), although it is just as likely that Truth is showing his true personality after years of cool political veiling.

Trivia

 * His name is ironic, like the names of all the other Hierarchs, as he is given no mercy by Truth, and he showed no mercy neither to Humans nor to the Arbiter, whom he wanted dead. Though it should be noted that he showed mercy to the Prophet of Regret, but this could simply be seen as discrimination, considering that Thel 'Vadamee and humans are of a different species, whereas Regret and he are both San 'Shyuum.
 * He was once in charge of the surveying and weighty inspection of the centered Forerunner Dreadnought.
 * Mercy managed to become the third Prophet by being at the right place at the right time: He heard what the "Oracle" inside the Dreadnought had to say about how humans were the descendants of the Forerunners and that it had to bring them to the Ark, almost killing millions in the process. So in conclusion Truth, not wanting the information to be discovered, asked him if he would fill in the place as the third future Hierarch; Regret already being the second, to which he agreed.
 * Philology is derived from the Greek terms philos (φίλος) meaning love and logos (λόγος) meaning wisdom. Philology is more accurately defined as "an affinity toward the learning of the backgrounds as well as the current usages of spoken or written methods of communication". In addition, they are also known as "lovers of wisdom".