No one should presume to own the Endless and the Dreaming, though Neil Gaiman and DC are the ones allowed to make money from stories about them. There is a reference to an event in the spinoff series Lucifer, but you don't need to have known about it beforehand.
I found this fic an interesting exercise in showing a more rounded perspective of the Corinthian, especially his very small protective side.
"You wished to see me, Lord?"
Dream shifts uncomfortably in his throne, and finally decides to stop caring and turns it into a rocking chair. He can change it back if officials he needs to impress arrive. The Corinthian raises a toothy-mouth-brow but does not comment. "I, well, I wished I…somewhat…to grant you…um…a boon. For your service."
"It was only what was commanded."
"I am referring to your service to Daniel. The memories of Morpheus are the stronger, but I still recall the child's life as well." He thinks of the agony of the fires, and vaguely remembers delight and safety at someone saving him and carrying him in strong arms, taking him to his beloved dreamland. "You were willing to give up your life to protect me, you, only a few days old."
"So I may ask for a favor?"
A soft, shy smile. "Take off your dark glasses, Corinthian. I would see you as you are."
This was the first time anyone had smiled at the nightmare while all his teeth were visible, and in that place in his chest where loyalty and duty resided (in the stead of emotions like "love" that he was not designed for), he felt warmth. "If it's not too much…you see, I dream too, about him, the other one of me,and things he did which I must never do…" His eyesockets chime in, never, never, wrong, bad.
"I will grant anything which is in my power to give."
"Lord, if you could make me not be so hungry…or, failing that, some acceptable way for me to feed this hunger…"
"O weary woman, dream of Valhalla. Snake, if you would kindly hold your venom you may dream of Ragnarok."
"What's this about then, Dream-weaver?" Loki asks, knowing his visitor by both words and voice.
"I am unsure if you are aware that Morpheus has passed on the identity?"
"Sigyn babbled something along those lines a while ago, but I wasn't paying much attention. I caused his downfall after all?"
"No. You helped prepare his replacement."
"Not any longer. Well, mostly not. You were interrupted before all the child's mortality was burned away. A rather painful process, I remember, but a necessary one. I am here because I feel your retribution was disproportionate, especially since so much evidence suggests that Morpheus used you as a pawn."
"Coming to set me free again? I would certainly have greater difficulty stabbing you in the back." At this he nearly breaks into inane laughter, but he reins himself in.
The Dream-weaver sighs. "Though I dislike cages, I acknowledge that some beings need to be caged for the safety of others. And I have no quarrel with proud Odin. However, I know that you neither sleep nor dream in this punishment of yours. I am able to grant you such temporary escape from sorrow as mortals receive."
"What do you wish in return?"
"I would not have you be under obligation, so the gift comes with a price. One in four of the times you dream, you shall have a nightmare that must run its full course before you are permitted to wake. The other three-fourths of the time you may dream of whatever joys you crave."
"I highly doubt I could have a worse nightmare than my waking situation, in case you haven't noticed."
"So will you accept?"
Instantly, Loki finds himself seeing, with the eyes of a dreamer, the castle where he last could see in waking life. His neck is solid and sturdy, and he is free to roam through echoing rooms and staircases. He is unsure yet whether this is a good dream or a nightmare.
He hears feminine giggling from a room nearby. Ah. So that's it. He sets off in search of the sound. He comes to the room where he thinks he is satisfied to have any woman present, dream-creature or no, even if she looks like Sif. And, if he were put to it, pretty much any person or creature willing – or even simply not able to fight back too hard.
It's dark. He flicks on the light. A harsh fluorescent one, as it turns out.
And finds the door locked when the light reveals the Corinthian, playing with a pocketknife and with various other unpleasant tools neatly arrayed around him. "The new Dream is good at killing multiple birds with a stone, isn't he?" the horror says reflectively. And his left eye says you frightened the child and he remembers and his right eye says, oh how I missed you…
Loki screams, temporarily forgetting the upside to this deal, thinking of nothing but how this one little nightmare made him pathetic misery when gods and Endless could not.
"We've got eight hours, so you might as well take a seat." mmmhmmm…
The next time Loki dreams, he finds himself on the actual grounds of the Dreamweaver's castle. It is his full right to seek out pleasure gardens or wish-fulfillment hamlets where he can play the most marvelous tricks on Asgard in general and that clod Thor in particular, but his outrage is too intense. He storms his way to the gates.
The idiotic raven, flapping about the parapets, seems alarmed by his presence, but the griffin explains that sleeping gods are as welcome as any other dreamers.
"Stay on your path," the dragon warns, not unkindly.
He comes upon Dream talking to one of his servants, who has a pumpkin for a head. "I am not devaluing your contributions, Mervyn, but your constant references to me as 'The Kid' is perhaps not striking the right tone among the staff."
"Y'know I was just kiddin' boss." Mervyn says nervously, fingering his broom like it will protect him.
Dream is rolling his emerald back and forth between his fingers and speaks as if to the bauble rather than subject. "Though, if you must give me some nickname, I do prefer it to 'Tall, Pale, an' Interestin'.' On the continuum of excessive familiarity, the least offensive is 'Daniel' which is merely inaccurate, followed by 'Dream 2.0', 'Dandelion', and 'Emerald Lad', with the most offensive being, um, 'Ghost Boy'."
Then Dream spies Loki glowering at him. "That will be all for now. I think the Subcontinent of Coma Victims needs maintenance, as usual?"
"This is hardly the most formidable presence," Loki grumbles when the creature trudges away.
"Would you have a seat, friend?"
The chair that has materialized is comfortable almost to a fault, and in fact might be difficult to extricate himself out of. "I am not your friend."
"A pity. It is difficult making new ones, with all the other adjustments of regime change."
"This isn't funny!"
Dream steeples his fingers. "It was not meant to be. It was meant to be an honest bargain far kinder than the sort you used to make with others, which happens to conveniently intersect with what the Corinthian requested from me."
"You tricked me."
"Said a god of trickery. But I never lied to you, Loki. You could not say the same to me. For example…" here his eyes flashed briefly, "there was nothing 'nice' about those fires."
He wonders how he would have done things differently if he knew the child he was sent to abduct would eventually have so much power over him. "But…"
"I would suggest you enjoy yourself in your remaining time here, before paying your dues once more. Fare well."
The most distressing thing about the Corinthian isn't, actually, the fact that he has sharp mouths where his eyes should be. It's how handsome and ideally formed the rest of him appears. The slightly wrong is more unsettling than the ghastly fright. Your defenses are weaker.
Similarly, the most distressing thing about Loki's next nightmare is the fact that they are not in any kind of torture dungeon or other pain-related venue. They are on a stage before an empty few rows of chairs, a modern meeting hall. There is quite an unremarkable table at which they are seated across from one another, and Loki's portions of food and wine look nothing less than appetizing.
The problem is that the Corinthian's place setting, instead of a normal plate and set of cutlery, is a bowlful of eyes. Also, the fact that Loki is unable to get out of his chair no matter how much he strains himself.
"I wouldn't keep trying," his captor says drily. "While I'm your nightmare, I can control all aspects of the setting, much the way Lord Dream does in his castle. Have some grapes. I hate that I remember how my predecessor ate grapes when he had to eat some human food, to blend in, but this is what the room provided."
Loki's curiosity overcomes his revulsion. "What do you mean, 'predecessor'?"
The Corinthian removes his sunglasses, folding them neatly and putting them in his shirt pocket. "Morpheus created the first Corinthian tens of thousands of years ago. All went well until Morpheus' imprisonment and that Corinthian decided he could do whatever he liked. He went into the waking world and killed pretty mortal boys for forty years. He was punished by being uncreated."
"That's why you challenged me to…"
"You're still not eating anything. It won't do anything to you." He scoops up an eyeball and puts it in a socket. The sound is a sickening 'shlormp' as the tiny mouth begins to chew. He adds in another. "Yes. In case you're wondering, this is what it looked like shortly after I got the information I needed from yours."
"Don't…talk…with…your…eyes…full…" Loki wheezes hysterically before vomiting onto the floor. The vomit promptly vanishes.
"As I was saying, Morpheus decided he needed a new Corinthian to serve him. Though you may have difficulty believing it, I am the far more ethical and good-natured version." He experiments with putting a little salt on an eye before inserting it.
"You are a sick motherfucker."
"I never had a mother, or the slightest interest in women either, it seems. And you are one to talk, horsefucker."
Maybe if he wants people to stop mentioning that, he should stop bringing it up in his boasts. So he doesn't argue the point. "Why are you doing this, anyway? Is this what you're for, to eat the dream-eyes of dreamers?"
"No. I am meant to show men their own monstrosity. But this – you, me, here – this is not work. This is reward."
"I have never had a god's eyes before. I doubt I will again." The Corinthian takes a sip of what might be wine and what might be fresh blood. "It's not my fault sex, food, obsession, and violence are all bound together in my head. I'm a nightmare."
On the third night the Corinthian and Loki have together, the Corinthian abruptly stops what he's doing. Loki manages with great effort to turn his head and, through the eye he has left, see the toddler in overalls staring up at them.
"Why?" the child asks fearlessly, though the Corinthian's hands are covered in blood, and his eyeteeth with aqueous humor.
"You shouldn't be here," the Corinthian says, with unaccustomed softness. "I'll take you home."
If Loki were currently able to speak, he would be making some jibe about inappropriate relationships. But he cannot, and he is relieved when the Corinthian puts aside his tools and takes the child's hand, leaving him alone as they walk away together.
The Corinthian wakes and realizes he isn't alone. He is curled in a ball with his Lord, who is not asleep, as the Endless never need sleep.
"I hope you can forgive the liberty," Dream says softly. "I feel safe here."
"My master may do what he pleases," the Corinthian replies, and cautiously runs his fingers through the soft white hair.
Loki never knows that, when Lucifer visits him and burns the snake tormenting him in exchange for a favor from the god, the idea to do so first occurred in a dream.
The Corinthian becomes increasingly more relaxed in his dream-meetings with Loki, and eventually merely waves in the background of other, tamer nightmares. For his discretion and care, his Lord newly furnishes him with capacity to love, hate, fear, and hope.
This new incarnation of Dream becomes known for not taking lovers (and his both female and male) for any lengthy period of time, but only for a night, then sending them on their way. He is also known for feeling especially close to those residents of the Dreaming who were kind to a boy named Daniel Hall, some time ago.