Can I go back in? (Part 1 Of The Family Series)

Who?

"you okay?" Jace asked quietly as he watches Clary's eyes flutter open lightly. She stretched her arms out above her head and moaned as the light hit her eyes. She didn't take long to cover them over before questioning what was wrong with her.
"You had some form of breakdown in your sleep and hit your head off of the bedside table. Possible concussion." He explained to her gently, trying not to startle her. After he allowed her time to process he got straight down to business.
"On a ... Lighter note? Magnus found out who this demon is and is waiting for you to tell us. He has only just found out before you woke so you didn't miss much." He chuckled softly.
"Never a dull moment is there?" She mumbled as she took Jace's hand and got out of bed, heading to Alec's office where they would find Alec, Magnus and Izzy. The room was thick with anticipation when they both walked in. Magnus stopped his blabbering about shampoo and payed attention to Clary.
"Ready?" He asked her, gesturing for her to sit down. They all nodded and stared, wide eyed at Magnus who felt slightly intimidated by his peers.
"You're greater demon is..."

"Do they know?" The voice asked as Jonathan stood before the source of it. Even Jonathan didn't know who it was. One of his master's little helpers that despised the blood of the angels. He stood before it quaking in the spot he stood in. The glare of its black eyes creating blacker black holes in the blackness it stood within. This was no greater demon that he had come across before, this was different, stronger, more possessive.
"I am almost certain that their warlock has figured it out by now and he wouldn't have hesitated to tell his friends and husband." Jonathan half spat the words out, trying not to disrespect the demon. He knew that if he made one mistake then he would be tortured in the most unbearable ways imaginable before he knew it for all eternity. His master had made that very clear.
"How is our hostage doing?" It asked with a snarl.
"That old mutt is doing fine. Doesn't know what him him. Keeps asking for his vampire friend, begging to know if he is okay." Jonathan half chuckled. His laugh was forced but definitely believable. The demon sunk back into the darkness and left Jonathan standing alone in the room. It was then that he noticed what the room looked like. It was once an old mine but it was now infested with odd bits of greenery and slime, he could see two pathways from where he was stood. One led to the prisons where there only hostage was crying in its cage. The other paths led to the network of tunnels where one of them Led to the food chamber for the demon along with his room. He had a Nast job really when he wasn't out on missions from his master, he had the joys on brining fresh mundanes to the demon so it could feed. Two  everyday was enough to keep the demon alive. Any more and the demon was too powerful to contain and they ouldnt have that.

The next morning Jonathan woke with a grumble. His sleep disturbed by the sound of the demon calling out his name in a cringing voice. It was like the sound of nails being dragged along a blackboard and it went straight through him. Causing him to shrivel up everything he heard it. He forced himself out of his bed and he shuffled toward the demon's quarters.
"Yes?" He asked bluntly, pushing his lower back forward with his hands.
"I need food!" It demanded.
"You need food, what?" Jonathan asked smugly. He knew he could get away with this first thing as the demon didn't have enough strength to inflict any kind of pain upon him.
"I need food please?" It asked politely. Jonathan nodded his head and scratched his back as he went to go and fetch another mundane to feed the monsted with. Has he got the mundane he found a note which read.

Wanna know who it is? Ask.
Your master,

The rest had been smudged by the dirt from around the room. He dragged the small girl who was kicking and screaming all the way to the greater demon where he threw her at it with all the force he could muster. Once the demon had finished feeding he decided he wanted to know desperately.
"Who are you?" He asked politely. The demon questioned his intentions and then slowly lent forward after a moment of teasing. Straight away he recognised the face of the beast. He was one of the fallen angels. He was the most known one of all.
"Lucifer? How?" Jonathan questioned with concern flooding into his flat voice.