You and Will walked tiredly back to your apartment. Will had teleported you into the middle of the forest, but you'd done the dirty work of digging Dipper's grave. Bill had flopped onto your sofa and refused to help. Night had fallen by the time you made it back home.
You opened the door to find Bill, still on your sofa, watching your TV and eating your Chipackerz. You froze. Will yelped and hid behind you.
"Bill," you said very, very quietly. "I'm not sure I want to hear the answer, but what are you still doing here?"
"Watching this movie and eating these delicious crackers! They taste just like chips!" he said cheerfully. You could tell he was willfully misunderstanding your question.
"And how long, exactly, do you intend to do so?" Your voice was frosty.
"Dunno," he said, stuffing another cracker in his mouth. "How long do you humans usually live?"
You stepped between him and the TV and leaned dangerously close to his face. His cocky composure wavered, and you could see the alarm in his eyes as you gave him a glare that could freeze magma.
"You mean to tell me," you were about two seconds away from committing your third homicide, "you intend to live here?"
"Look, kid," he said, leaning around you to see the TV, "you killed my contract holder. Ergo, my contract belongs to you now. Did Will not explain this to you? This is how deal-making demons work! Like it or not, you're stuck with both of us now!"
He chuckled nastily as you turned sharply to Will, who shrunk back under the force of your gaze. Wordlessly, you pointed down the hall. He slunk to his room, trembling, as you followed him in and slammed the door.
"Talk. Now."
His legs collapsed and he sat down hard on his bed. Tears were already running down his face, but you were too angry to go easy on him.
"I-I'm sorry! I was going to tell you, but-"
"But WHAT!? It seems like an important detail to leave out!"
He hid his face in his knees, retreating into himself the way he did when he was truly terrified. "But- I was afraid that if I t-told you, if you knew that y-you were my m-master, th-then you'd start treating me l-like Dipper and Mabel did..."
Instantly, your anger evaporated. You reached for him, but he jerked back with a whimper. You ran your fingers through your hair instead and stepped back to give him some space.
"Y-you'd really think that of me?" you were horrified, mostly at yourself. You stepped back further and closed your eyes. "I'm sorry, Will. I overreacted just now. But you should know by now that there's no need to worry, right? You know I'd never treat you like that, don't you?"
He shook his head and cried harder. I guess it takes more than a few weeks to undo years of trauma. You looked at him sadly, feeling like the world's biggest jerk. What can I do? Am I even capable of fixing him? For the first time, Will's complete emotional dependence on you felt like a burden too heavy for you to bear.
You knew he wouldn't let you get close until he'd calmed down, but for now you had another problem to deal with in your living room. "I'm sorry, Will," you whispered again, then left his room quietly.
Bill was still absorbed in his movie. You snatched the remote away from him and turned off the TV. "Hey!" he protested. "I was watching that!"
You got up in his face again, pointing a warning finger at his uncovered eye.
"Rule one. You will not antagonize, traumatize, torment or otherwise disturb Will."
"Where are you going with this?" he asked suspiciously.
"Rule two. You will ask my permission before performing magic on others, no exceptions."
"Now, that seems excessive," he protested.
"Rule three. If I tell you to leave, you have to go immediately and without argument for as long as I decide."
"What? That's unfair!"
"All interpretation of these rules will be left to my discretion. Exploiting loopholes will not be tolerated. Am I understood?" You held out your hand to shake.
"What do I get out of this?" he demanded. "I don't make deals without reciprocation, kid!"
"Did you forget already?" you asked coldly. "You're the one who wants to live here. Keep hogging my TV and eating my Chipackerz, and you have to agree to my rules." You renewed your offer of a handshake.
He stared at you for the longest time. You held eye contact with determination. Finally, he grasped your hand. Blue flames enveloped you both, sealing the deal.
You handed the remote back to him and left without another word. He turned the movie back on and went back to eating your food.
You paused outside Will's door and knocked softly.
"G-go away!" You heard him say.
"Will?" you said through the door. "Can I please come in?"
"Do you p-promise you're not mad?"
You opened the door. He was still huddled on his bed, crying. You climbed up next to him, gently peeling his arms from around his knees. He tried to pull away, but you held on to his hands.
"Will, please believe me. I'll never treat you the way Dipper and Mabel did. I know it will take time for you to trust me, and I'm not perfect. Sometimes I get angry, but I don't mean it. But please don't shut me out. It would break my heart to know you were scared of me."
"I- I know, but..." he trailed off, leaning into you and clinging tightly. You hugged him as well and slowly tilted so you both were lying down.
"But nothing, Will," you muttered, your face buried in his hair. "I'll stay by your side until I can see you smile again. You'll trust me someday. Just wait and see. And until then, I'm not going anywhere."
He didn't respond. You felt him trembling in your arms long after he'd fallen asleep.