Deus Ex Machina

Deus Ex Machina is the God of Time and Space and a major character of the Future Diary manga and anime. Co-creator of the Future Diaries alongside John Balks, Deus creates the survival game to make sure he has a successor to his title before his inevitable death. Able to manipulate time, space, and the laws of cause and effect, Deus is the most powerful character in the series and acts as the judge of the survival game.

Appearance & Personality
Deus is an extremelly large figure, towering with tens of feet tall. Barely humanoid in appearance, Deus appears as a huge creature made of machinery, possessing a large, skull-head head, sporting spiked purple hair and a crown, and he wears a large dark cloak.

Despite being god, Deus is very playful and laidback, considering most of his actions as games. He creates the survival game in order to choose a successor for his throne and title, but instead of just choosing one purpose, he makes the survival game in order to create a more interesting outcome, having multiple candidates to choose from, and possibly with a rather fondness for Japan given that all the participants are Japanese. He seems to be playful to terrifying degrees as he is completelly apathetic of the results of his fun, as seen during his first appearances that he had provoked a war for the simply sake of fun, as well as how the overall survival game involves the participants to literally kill each other through any means possible, no matter how dirty while most of them being openly insane, while Yuki who believed him to be his imaginary friend is the most normal-wise participant. During the game he's however a man of honor and does whatever he believes neccesary for the game to be as fair as possible, such as answering questions or create a special observer to collect info of the participants. Although far from a benevolent god, Deus is not without compassion and has in few occasions done good things without any personal profit, the survival game being the case as he used the game to choose his successor before the world dies, saving Minene Uryu from death despite how much she hates him, to become a participant, despite making it clear that she was not forced to do so, etc.

Also, the fact that he interacts with few humans seemingly without any explanation, implies that he's in fact fond of some humans, or at the very least those who he finds to be interesting.

Character Outline
Deus is an ancient deity who has ruled over time and space and the laws of causality. As god, Deus is omnipotent and is able to create and alter causalities through time and space. It is implied that he may be able to rewind time, but leaping back in time can create parallel worlds. Despite being a god, Deus is unable to resurrect the dead. While reviving a body is possible, without a soul, the dead cannot come back to life by any means. Deus has control of the Akashic Records, the universal compendium of knowledge and history. Deus is shown to be able to create artificial lifeforms, namely Aru Akise, revealed to be his "Observer" in the survival game to keep track of the ever changing futuries of the diary owners.

Deus operates from the Cathedral of Causality, depicted as a large domed building coloured with a purple tint. Deus sits in a large throne which hovers above the ground. The cathedral also has an arena where the diary owners, Deus and Muru Muru meet for occasional meetings. The arena is covered with an eternal cloudy sky, revealed to actually be a cover for the Akashic Records.

He remains oblivious to the existence of the first alternate world, implying he only has power over the time and space of the universe he lives in. Deus at first makes the choice to not interfere with the events of the game and watches merely as an observer. However, during the second game, when Yukiteru Amano discovers the three corpses in Yuno Gasai's house, the whole pre-planned events of the second survival game are altered, and Deus does not act to restore it, finding an alternate path all the more interesting. He eventually abandons his intention to not influence the events of the game after Muru Muru does. He wishes to make the game as fair as possible, but outside influences force Deus to play his hand near the end of the game to ensure it runs smoothly. He is even willing to abandon the game all together, as seen in the third world when John Balks puts a halt to his Future Diary project, cancelling out the third survival game.

Deus appears to have extended relationships with the different diary owners. He is rather fond of Yuki, at first posing as his imaginary friend and personally makes him the "First" diary owner. Deus openly supports Yuki throughout the game, unphased by Yuki's mishaps and believes it is all part of Yuki's future to win the game. He also has a unique relationship with Minene Uryu, who does not believe in god and wants nothing more than to rid the world of the very concept of a deity. Minene has a love/hate relationship with Deus, openly hating him but is willing to ask him for advice, and even protests to receiving a portion of his powers when the time comes. Deus views Minene as an ally, using her to put a stop to Muru Muru's plans. Deus and John Balks seem to be good friends, creating the Future Diaries together. Balks seems to care for Deus, but also uses Deus' needs as an excuse to extend his own plans in the survival game, requesting that Yuki and Yuno be eliminated from the game to speed it up before Deus dies.

It is never explained why Deus is dying, but his death causes the universe to be swallowed up in black holes. Deus is succeeded three times in the series. In the first world, Yuno becomes his successor, Yuki in the second, and finally Yuki and the third Yuno from the third world.

The First World
Not much is known of Deus during at this except that he was dying as well and started with John Balks to choose a successor, and overall oversaw the game from beginning to end without any apparent need to act. It is suggested he died at 28th of July shortly before Yuno won the game.

The Second World
Deus as he appears through most of the series. He's initially shown as Yuki's imaginary friend, and eventually gives him his Random Diary like the other participants received theirs. When Yuki is revealed by Yuno that she possesess a diary, he reveals to Yuki that he never mentioned he was the only one. Following this, Yuki and Yuno face The Third, Takao Hayama  and defeat him and immediatelly Deus invites the remaining participants and explains the Survival Game to them, its rules and the basics of The Future Diaries and call Yuki (by this time The First) as his favourite candidate.

Deus appears expressing amazement towards Yuki who created a large change on the future after he peeps on a secret room on Yuno's house. After this event Deus keeps overseeing the game until Muru Muru would accelerate things and force The Fourth, Keigo Kurusu into action, which would prompt him to be much more cautious about his servant. He does not take action until the appearance of The Apprentice Users where he invites Yuki (and possibly the other participants) into answering their questions about them.

He appears later when Yuki's mother is killed by his father, and Yuki asks Deus to revive her, to which he says he can't followed by Muru Muru who says he should become God if he wanted things to become normal. He's seen again talking with Muru Muru after Minene's attack on John Balks, before feigning about going to rest. Being visited by Minene to ask him about Balks's Diary, Deus at this time uses the chance to transfer some of his powers to her so that she could stop Muru Muru and her schemings (although Minene wouldn't be aware of this until much after) and reveals to Minene the nature of Balks's The Watcher and how he along with Balks created The Future Diaries.

Following Balks's death Deus is at this point at the verge of death with the world starting to collapse. Aru Akise visits Deus to confirm if it is possible to bring resurrect the dead. Deus answers that only the body can be brought back, but the soul is an impossible task even for him. Learning the truth Akise tries to warn Yuki, but Deus stops him and reveals to Akise that he's his creation serving as an observer of the game to gather information, and since he has outlived his role he starts to slowly vanish him into the Akashic Records as Akise tries to prove that he has a will of his own. Deus gives him the chance to prove so, but fails and almost vanishes him completelly until the timely arrive of his own diary The Detective Diary provided by The Eighth, Kamado Ueshita therefore proving that he was capable of something outside Deus's plans. Amused at this Deus lets him live on his own accord. Deus dies shortly after this with the only thing remaining alive being his core which would last for enough time to grant the winner the prized godhood. In this state he warns Muru Muru that she must allow the game to run properly as she's restrained by her seals to do so.

The Third World
Deus's core of the second world is given to Yuki after he wins the game, while a third Deus is approached by Balks who saw his own demise from The Watcher by reading the diaries of the second world's participants who time leapt, to cancel the Future Diary project, therefore nullifying what would be a third game. 10.000 years into the future of the second world's timeline Deus appears with the first and third incarnations of Muru Muru connecting the timelines of the second and third world, along with the Yuno of the third world who was given her first incarnation memories which allow her to survive. Mostly because Yuki and Yuno have won the previous games and possibly because of convincing from the two Muru Muru, Deus calls off the game and happily accepts both Yuki and Yuno as his successors, therefore it is implied that he dies at this point or if he's alive he no longer is a god.