Metatron

Metatron is an angel and the Scribe of God who recorded The Word of God. Out of fear that the Archangels would steal the information of God from him, Metatron left Heaven and hid among native American tribes and modern day Americans until discovered by the Winchesters. Metatron then sought to take vengeance upon the other Angels for forcing him to leave, using Castiel to make a spell writen on the Angel tablet, and emptied Heaven of all Angels. Upon the disapointment of being alone in Heaven, Metatron is currently working to rebuild with Gadreel as his second in command.

Background
The Word of God was inscribed on multiple stone tablets in an ancient language that almost all beings, including angels, cannot read. One of these tablets containing the Word had instructions on how to kill the Leviathans should they escape from Purgatory and another one tells of how to lock the demons in Hell forever. Metatron was later mentioned by Kevin Tran when reading the Word of God to Crowley.

While Kevin was reading the tablet on demons, the prophet saw a personal note by Metatron. It mentions the angel taking leave of his master and letting humans take responsibility of the compendium of tablets.

Although first presumed to be an archangel, Metatron himself revealed that he was simply a common angel with a secretarial position. He was chosen by God sometime before God's departure from Heaven. Metatron received instructions to write down the Words of God. Metatron stated that, before he was chosen to be the Scribe, he lived a life of isolation and obscurity among his fellow angels. As such, he was overjoyed to be chosen above all others as God's scribe.

When God left, the archangels despaired, and soon after began conspiring to claim the universe as their own. This prompted Metatron to distance himself from Heaven, so as to protect the Words of God and to prevent the archangels from claiming the tablets.

He hid himself along with the Native American Tribe of the Two Rivers, where he blessed the tribe with immortality in exchange for stories and books.

Season 8
Sam and Dean eventually tracked him down, in his vessel Marv, and convince him to aid them. He rescued Kevin Tran and revealed that the third trial is to cure a demon.

Metatron had a plan all along to bade the time by until Heaven would ultimately fall, pretending to have a wanting to save it, Metatron would recruit Castiel to help him complete the 3 "trials" that would apparently close Heaven off, doing this, Metatron believed that he could close angels off into a space where they'd need to sort out their own problems. The first trial, to kill an angel/human hybrid called a Nephilim, went successfully. The second trial, to take the bow of a Cupid, was also a victory, Metatron is then captured by Naomi and brought to Heaven to be tested on so that Naomi could see into the scribe of heaven's eyes. Once she does, however, she becomes aware of Metatron's plans and warns Dean and Castiel that Metatron has been lying to them, at first they don't believe her, but once Kevin confirms (or at least tries to) that neither of Metatron's trials were even scribed onto the angel tablet, Castiel travels to Heaven to find out, despite Dean telling him to wait while he saved Sam. Once Castiel arrives, Metatron reveals that Naomi was telling the truth, he captures Castiel and ties him to Naomi's operating chair and steals his grace as part of the third trial, revealed to be a spell to expel all angels from Heaven, rather than seal them in. With Castiel's grace gone, he is now human, the spell is complete and before Castiel is to fall, Metatron tells him to live a normal life, get married, have children, and once Castiel dies, and his soul reaches Heaven, to come back to Metatron, and tell him what his life was like as a mortal being, Metatron then seals Heaven off, and thousands of Angels fall from the sky around the world, the Men-of-Letters headquarters is put on red alert as the hierarchy of Heaven has collapsed, Metatron is last seen teleporting Castiel out of the operating room. Shortly afterwards, the angels fell. This made Metatron directly responsible for the deaths of several angels, including Sophia, Azrael and Ezekiel.

Season 9
In "Holy Terror", Metatron reappears. He reveals that he still has access to Heaven, and contrary to his earlier thoughts of enjoying being the only angel still there, he finds it rather boring. He contacts Gadreel with an opportunity to serve as his second-in-command, and informs him that he can allow certain angels to return to Heaven. He explains that they are going to be rebuilding Heaven with a select few angels allowed inside, and Metatron will rule as the new God (although he will simply be known as X). As a test of loyalty, he orders Gadreel to kill somebody he regards as a threat to their new order, and sends him after Kevin Tran. Gadreel kills Kevin and goes to rejoin Metatron.

Personality
For an angel, Metatron appeared to be quite human-like, openly expressing emotions such as joy, admiration, disdain and sympathy. He does not show the arrogance or pettiness that other celestial beings do. He admired humans, due to their use of free will, and particularly enjoyed their stories, seeing it as a great example of free will.

However Metatron disliked other angels, and was fearful and suspicious of them, particularly of the archangels. Metatron appeared benevolent and helped humans with his powers. However, he was suspicious when dealing with those he did not know. Metatron is also very logical and intelligent.

However, he proved to also be very bitter, vengeful and manipulative with angels. It was revealed he wanted to expel all angels from Heaven as revenge for his own exile. So he tricked and manipulated Castiel into completing the "trials" and expelled every angel from Heaven.

Metatron later reveals he's changed his mind, as he got lonely upstairs, and now plans to rebuild Heaven, with a select few angels. He also reveals his opinion of humans isn't as high as he orginally stated, revealing although he doesn't hate them, he does find them "chaotic" and "exhausting" due to their endless expression of emotions and desires and claims that isolating himself was the only thing that kept him sane while he was on earth.

Physical appearance
Metatron's true form was able to deteriorate the flesh off of Crowley's vessel. It is unknown what he truly looks like, however, as an angel, he does have at least two large, feathered wings. On Earth, he manifests in the embodiment of a middle-aged, pot bellied, bearded man.

Powers and abilities
Metatron has the power of regular angels as well as few rare ones that are exclusive to him as God's scribe, and is able to use them all despite leaving Heaven for a long time, similar to seraphim and archangels. Additionally, as the Scribe of God, he was able to erase any Enochian sigils planted to ward off angels. Apart from his powers, he was incredibly intelligent. He was able to avoid detection by Heaven's forces for thousands of years.
 * Angelic Possession - Metatron possess a human vessel to exist in corporeal form.
 * Cosmic Awareness - As the Scribe of God, he articulated several documents referred to as the Words of God. He, therefore, possesses an acute knowledge of many creatures, including demons, Leviathans, and even his own kind. He also possesses a keen sense of spiritual realms, although he had no knowledge of who the Winchesters were, that Michael and Lucifer were trapped in the Cage or that Gabriel and Raphael were dead, due to him purposely separating himself from Heaven, however he caught up quickly.
 * Teleportation - He traveled from Heaven to Earth to relinquish the tablets. He also teleported across the room when confronting Sam and Dean. He was able to teleport Kevin with him to safety.
 * Immortality - Metatron was present during the creation of Earth, making him over 10,000 years old.
 * Healing - Metatron was able to heal Kevin Tran after Crowley nearly strangled him to death. He also healed Castiel after having cut his throat with an angel blade to extract his grace (even the blood from the wound disappeared with not even a smear).
 * Power Granting - Metatron was able to grant the Native Americans who gave him stories a much longer life than humanly possible.
 * Holy White Light - Metatron used this ability when saving Kevin Tran by burning Crowley. Interestingly, the Prophet's eyes lit up when Metatron arrived and used his white light. Whether this suggested Metatron temporarily possessed the prophet or merely channeled his power into the prophet is unknown.
 * Removal of Angel Warding - As the Scribe of Heaven, Metatron can apparently erase the warding without being affected by it.
 * Spell Casting - Metatron was able to cast a powerful spell to expel all angels from Heaven.
 * Apporting - Metatron was able to send Castiel back to Earth after he stripped the latter of his grace.

Appearances

 * Season 7
 * Reading Is Fundamental (Mentioned only)


 * Season 8
 * We Need To Talk About Kevin (Mentioned only)
 * The Great Escapist
 * Clip Show
 * Sacrifice
 * Season 9
 * I Think I'm Gonna Like It Here (Mentioned only)
 * I'm No Angel  (Mentioned only)
 * Holy Terror 
 * Road Trip 

Trivia

 * Metatron is an Archangel according to Jewish cultures.
 * Metatron's name means "Voice of God" in Hebrew.