[Character name] The Inorganic Angel Rosiel
[Age] Appears to be in his early twenties.
[Canon] Angel Sanctuary
[Point in time taken from canon] Post-chapter 95, after he orders Lucifer to massacre the officials guarding Layla, whom he had just driven insane.
[Background]
Link to Wikipedia. In the beginning, there was YHWH. YHWH created the seven levels of Heaven, and the seven levels of Hell - and man's world, Assiah, in between their lot. YHWH created Adam Kadmon, a perfect, genderless angel with six wings, with great powers and the ability to control time. From Adam's image YHWH created more angels, first and foremost the keys to YHWH's dimension - Etemenanki.
They were the Inorganic Angel, Rosiel, born out of his twin, the Organic Angel - Alexiel. Rosiel was born a hideous creature: even his caretaker angels were afraid of him, and drew away, whispering amongst themselves.
Of course, he didn't know what they were talking about, until he saw his reflection in a pool of water - and even he himself was disgusted by his appearance. He was born to age in reverse, getting younger and younger through millennia; with this youth came rot and madness. Rosiel knew this, and acknowledged that sometime in the future, he would turn completely insane.
He did not want this. He was an angel of benevolence - a great example of this is that he gave a low-level, bodiless angel a body of its own - and he cared for his lambs. So he turned to his sister for help. She was to kill him before he lost his sanity. It was for the better good.
Alexiel, however, appeared to be unsympathetic. While Rosiel walked the path of light in Heaven, in Atziluth (its highest level), where he was lavished with praise as the beloved of God, Alexiel was caged in the garden of Eden. Rosiel didn't know why, but his sister would not even look at him when he visited, even when his hands bled as he clung and pleaded for death through the thorny bars.
So he assumed: Alexiel was jealous of the love showered on him. She was jealous of the beauty he possessed. Alexiel hated him, even though Rosiel loved her above everything else. This thought consumed him as he started the slow and complete descent into madness.
And then the First War between Heaven and Hell started; the latter led by the illustrious Lucifer Morningstar.
The angels of Heaven mercilessly slaughtered the agents of Hell, and even those who were unfortunate enough to get caught in the middle - the mostly-neutral Evils, who merely shared dimensions with the fallen angels who were Lucifer's comrades. Alexiel, who had no particular alliance with either of the two, was disgusted by this, and she defected to the side of the Evils. She rebelled against God.
Rosiel was still on Heaven's side during this, and as a result, the siblings were forced to fight each other. Madness was starting to take firm hold on the Inorganic Angel, and when they were face-to-face, he'd laughed in front of her and asked her if she hated him, because he was the beloved of God - and he'd dared her to kill him because of that hatred.
She wouldn't kill him, though, and Alexiel sealed her brother into Assiah instead, using forbidden magic. Rosiel only knew that his sister hated him as she did, that she rebelled because God only loved Rosiel and not her, and it was with this mindset that he was forced into sleep that lasted centuries.
He would wake up again, in modern times, by his still-faithful servant: Katan, the low-level angel that he had given a body. He knew Alexiel's punishment for rebellion: the brand of a fallen angel on her breast, and an endless cycle of reincarnation into miserable lives that had violent deaths. He wanted to seek her out, to take her beauty into his own rotting hands.
And Rosiel found out that his sister had been reincarnated into Setsuna Mudou. From then on he made it his job to try and wake Alexiel's consciousness within the boy, while unsettling Heaven's current military junta. After all, he held the highest rank within it, and after his forced sabbatical, it was only right that he took back his rightful place.
[Personality]
First of all, and most importantly, Rosiel is mad. Undeniably, excruciatingly, mad. He knows and acknowledges this when confronted, in fact, he knew that he would lose his sanity long before it happened. That was why he asked Alexiel to kill him in the first place.
Which leads us to his next, often-overlooked characteristic: underneath it all, Rosiel is benevolent. He's retained this, no matter how vague and twisted, all throughout the series - most notably towards those people whom he is closest to. This is evidenced by his attitude towards Katan: while the intention with resurrecting the angel with his poisoned threads of life might be questionable, there is still the fact that he does all that he can to keep Katan away from him when he knows he will lose his sanity completely.
For all his outward narcissism, and his crippling need to be called beautiful, Rosiel has no sense of self-worth. He loathes the ugly creature that he is, the ugly soul that he harbours, but he still believes in others, at what they can accomplish; this is why he gives his wings (and by extension, his powers) to the protagonist of Angel Sanctuary. Rosiel hated the world that he thought loathed him with all his heart, but he still planned to walk down the same path as them. He'd never told Katan that he loved him, even though it was evident that the cherubim was precious to Rosiel.
Moving on to his more apparent facets, though: Rosiel is manipulative, through and through. He prefers moving from the shadows, but he will not hesitate showing how powerful he is - he likes to casually assert his superiority, and he likes to watch them squirm under his influence. He sees most mortals and supernatural beings as lovely playthings; beings that would amuse him until he gets tired of them and threw them away.
However, there are exceptions to this: two of them being his sister, Alexiel, and his attendant, Katan.
Alexiel loved her brother. She didn't hate him, she never did. She was told to stay away from her twin by YHWH, if she wanted him to live - and she did. YHWH created the animosity between the twins because they were the keys to YHWH's palace, and ensuring that they hated each other would mean that there was no chance for YHWH's palace to be stormed. They were both victims of the whims of an all-powerful being. Rosiel does not know this, and believes that his sister hates him.
They are two sides of the same high power, and Rosiel craved Alexiel's approval and acceptance - so much that he tries to anger her current mortal incarnation, Setsuna, in order to coax her out and assimilate with her. Alexiel is the Organic Angel, and one of her characteristics is that her body cannot die, and always regenerates - with this knowledge, Rosiel aims to make himself beautiful again, taking his sister's eternal supply of beauty for his own. Deeper than that, he wants to be with her, to be loved by the only other creature he felt would understand him.
Katan is a different story. He was a low-level, bodiless angel, called a Grigori, who had obtained consciousness. Rosiel was still at the height of his sanity back then, and he gave Katan a body, and a challenge for him to work hard and meet him in Etemenanki.
The angel persevered and worked hard, rising up in the ranks, in order to obtain enough authority to be able to enter Etemenanki, the highest level of Heaven, and to offer his gratitude to the Inorganic Angel, the highest-ranking angel in the military. When they met again, Rosiel pretended not to recognise him. Katan broke protocol and approached his superior, and Rosiel told him off and took him away for a 'personal punishment'.
It turned out to be that Rosiel did remember him, but it wouldn't be good for Katan's reputation if word got out that he knew Rosiel personally. Rosiel was quite proud of who he considered his protegé had accomplished, and continued to guide and help Katan whenever he could.
They formed a close bond of master and servant over the centuries, and Katan would sometimes see the monster that his beloved angel would become -- but he did not falter. He was the only one who heard Rosiel weeping because of his sister, and even if he didn't fully understand why Rosiel was so sad, he still tried his best to comfort him.
After Rosiel woke up from being sealed, however, we can see that the relationship had degenerated into something far more twisted; he had claimed Katan for his own, and his own only. He was not even allowed to die, and Rosiel force-fed him one of his poisonous pills of life in order to bring him back. He constantly seemed to take Katan for granted, ordering him around with no regard for what the cherubim felt.
However, this is not true. Rosiel fears losing Katan, the only person whom he felt loved all of him, insanity and all. He covers up his insecurities in relationships with harsh words, honey-sweet lies, and orders, with pain inflicted and outright rejection.
He considers himself above all others, except for Alexiel, because he knows he is half of the most powerful angel in existence. Rosiel has the crippling need to be called beautiful, to be praised, because he knows he's rotting alive and descending further into madness.
[Abilities]
&bull he can create higher-level angels out of low-level ones
&bull time magic (he can speed up and slow down time)
&bull being a gamebreaker in general
&bull captain pills and golems; being the Inorganic Angel, he can create automatons out of unsuspecting beings by feeding them parts of himself, usually in the form of a pill.
&bull teleporting between planes of existence
&bull downloading data and information into himself: Rosiel is not alive, in a sense; he does still bleed, but he can repair himself almost instantly. All things inorganic fall under his control -- as a result, he can very easily hack into messages/data, control appliances and other inanimate objects, etc.
&bull controlling the elements - it's been shown that he can control the weather.
&bull
possessing bodies, creating replicas and illusions ---
&bull bugging the living daylights out of Katan and everyone else ever
&bull being passive-aggressive
&bull being a cool dude in general, if not mad
&bull having the fashion sense of a couture designer
&bull being fierce. LIKE A BOSS. he can work it, yo.
&bull crossdressing! he's been mistaken for a woman once.