Upon the demons return, he noticed several things wrong with Dipper- things that weren't because of the demon, or their relationship status. Things that Bill knew had to do with the wolf bite. The first was purely Dipper's reaction to the change; every time the moon rose, even though it wasn't a full moon, his entire body would go rigid in fear. Bill was vaguely amazed nobody else had noticed the teens obvious distaste of the moon.
The second was more obvious; when he smelt things and was trying to identify them, he smelt like a dog. Inhaling rapidly several times before snorting and telling Bill what exactly he was smelling. On top of that, his sense of smell had improved tenfold overnight. Dipper went from being unable to identify Mabel's perfume when it was right in front of his face, to being able to identify it even when they were clear across the house from each other.
Whenever they went outside and they were trying to follow something, Bill would notice the teenagers nose twitching, trying to follow the scent like a dog, but the teenager fought against it and downright refused, face reddening in embarrassment. It got redder when Bill said it was cute.
Another of the more noticeable changes was Dipper was more energetic. Not to say he moved around more than usual, he still loved loafing, but when he did go out to do something, he didn't tire for hours, even when Bill was beginning to feel aches in his legs and had to revert to his demon form for rest. Dipper would keep on going, not even realizing how long they had been out, until either Bill pointed it out and said they should go home, or the moon came out. And if it was the moon Dipper would stiffen for a brief moment and then turn and bolt back through the woods toward home.
The most alarming of the physical changes, however, was one just such an occasion, when Dipper had been running home to get away from the moon, and had dropped onto all fours and bolted through the brush. Bill had frozen where he was, unsure how to react to what he had just seen.
Dipper's mood was effected as well, but not as severely as Bill had initially thought. It became quickly apparent, however, that Bill had made a mistake when brushing off the teenager biting him that first night. He had assumed it was a wolf thing, but the teenager hadn't tried it since, so he assumed it was over and done with, and swept it under the rug, so to speak.
How wrong he was.
BILLDIP
The morning started normally- well, normal for the Pines family and their demon, and Dipper came downstairs to the smell of Mabel making blueberry pancakes- just like he had proudly announced to Bill upstairs only a few minutes prior. He took a seat at the table and Bill sat beside him, both their gazes falling upon Mabel. Bill's gaze was curious, Dipper's was hungry, and it sent a wave of discomfort through Bill's body, leaving him feeling unsettled and worried for the female twin.
"Pine Tree, are you feeling okay?" he whispered to the teenager, reaching out to touch his arm
Dipper jumped at the touch, whirling in his seat and baring his teeth at Bill, and Bill slapped a hand over the teenagers mouth before he could snarl and alert Mabel to their secret. Dipper's gaze relaxed and his features softened after he remembered it was Bill seated next to him, and he didn't need to be defensive, and Bill dropped his hand.
"Why wouldn't I be?" he asked cheerily, and Bill felt his earlier discomfort return
"No reason." he forced a grin "Just a question."
He didn't feel it worth mentioning that tonight was the full moon again. Instead he kept his worried golden gaze transfixed on the teenager, even when his gaze fell back to Mabel and a predatory hungry flashed through them again. Mabel turned around to call a greeting, and Bill got slammed with the urge to grab her and get her as far away from here as possible. Before he had the chance, Dipper leapt.
Mabel's screech filled the air a split second later, a crash filling the room as the frying pan fell from her hand and she hit the ground, her brother's body pinning her to the ground. A snarl escaped him and she screamed again
"Dipper what the heck!?" she wailed, bringing her knees up to his chest and pushing
Bill grabbed him around the waist and hauled him off of her, and she scrambled away, using her legs to push her backwards across the floor, the feral look in her brother's eyes terrifying her.
"Shooting Star, run!" Bill screamed, voice strained as he struggled to hold back the writhing teenager
She scrambled to her feet
"What's wrong with Dipper!?" she cried worriedly
"He's possessed!" he lied, gritting his teeth at the effort holding Dipper was requiring. The rest of his words were a hissed command from behind clenched teeth "Run! I can't hold him much longer!"
"I can't just leave him! Dipper- Dipper you have to be in there! Listen to me, its Mabel!" she tried, struggling to make her tone soothing
A warning scream from Bill was all the warning she got before Dipper broke free and took off toward her. She whirled and took off as fast as her feet could carry her, a screech escaping her, and she cried out when she was tackled to the ground again, all the air leaving her lungs in one strained grunt when she hit the floor. She struggled and went rigid when Dipper's teeth sunk into her shoulder. A screech escaped her and she began struggling once more, doing everything in her power to get her brother off of her, another cry escaping her when his nails dug into her flesh in an attempt to keep her still.
The weight disappeared suddenly and there was a crash. She looked over her bloody shoulder and Bill was taking off toward Dipper, the teenager rushing toward him with a murderous look in his eyes. Bill screamed for her to leave, and this time she didn't hesitate to take off, running as fast as she could out the door, a sob escaping her and she pulled out her cellphone and called Pacifica.
As soon as she was gone, Dipper went rigid. Bill slowly relaxed his defensive stance, and Dipper's horrified and wide eyed stare locked with Bill's wary gaze.
"What have I done?" he breathed, holding up his hands and staring in horror at the red liquid covering his fingers, knowing the same liquid was around his mouth.
Because he had attacked his sister. His loving, compassionate sister but did nothing to him but try to help, and support him, and pick him up when he was down. And he just attacked her.
Without another word, he turned and fled to his room.
BILLDIP
"Pine Tree would you listen to me for two seconds-"
"I attacked my sister, Bill!" he screamed frantically, voice cracking
Bill threw his hands up in exasperation
"You keep saying that but you're not listening to what I'm saying!" he huffed in annoyance "I told you, she's okay! She doesn't blame you! I told her you were possessed! We'll figure this out, Pine Tree!"
"No, No I attacked-"
"Dipper!" he snapped
"Bill!" he snapped right back, frustrated tears welling up in his eyes
Bill let out a noise of frustration and suddenly had their lips together, and Dipper instantly melted into the demons warm touch, heart skipping a beat when the demons arms gently wrapped around him and pulled him closer. The kiss told Dipper the words he hadn't been listening to; that everything would be okay. When they pulled away Bill rested their foreheads together, and Dipper offered a weak smile.
"Thanks." he muttered
Bill only snickered.
BILLDIP
It was twilight when Bill lead Dipper out of the house and into the forest, Dipper's entire body rigid, anxiety increasing the closer to dark they got.
"Okay, Dipper" Bill murmured softly, gently brushing Dipper's hair from his forehead so he could kiss his forehead tenderly "Will you be okay?"
Dipper's arms wrapped around him and he nodded slowly, hands fisting into the fabric of Bill's jacket. The demon returned the embrace for a moment
"I'll see you in the morning?" Dipper asked timidly
"Of course." he promised "If you aren't back to the shack by the time Mabel is up, I'll come get you." Dipper only nodded "I'm sorry I have to leave you, Pine Tree." he murmured "But it's safer this way. You know that, right?"
"Yeah." Dipper stepped away "I know that. Doesn't mean I have to like it, though." he offered a tired smile "I just want this night to be over."
Bill sighed softly and nodded in understanding, taking a step away from the teenager
"I know, Dipper. I'm sorry. If I could stay with you I would. But we have no idea how you're going to be when you change, and I don't know how my body would handle another encounter like the one we had with the wolf I killed."
"It's okay." he forced a grin "I understand. I don't want you to stay anyways. Not really. I don't want to hurt you. Not like I hurt Mabel."
"It's okay. She forgives you." he tenderly pressed their lips together once more "I'll see you in the morning."
"I love you."
"I love you too." Dipper whispered
Bill hesitated for a moment before turning and making his way back through the woods to the mystery shack.