The two of them watched Mabel and Norman over the next few days. Norman did a few things out of the ordinary-- such as, when a Frisbee was thrown at him it hit him in the face and he fell over, he smashed a window to get the door for Mabel, walked kinda funny, and when he fell in an OPEN GRAVE (Sylvia didn't know why there was an open grave. She didn't particularly want to) he reached up like a zombie. 

Finally, Dipper said, "I think we've got enough evidence to say that Norman is a zombie."

Sylvia shrugged. She didn't really know one way or another. 

Walking into the twins's room, Dipper said, "Mabel, we need to talk about Norman."

"Isn't he the best??" Mabel asked brightly, her eyes wide and happy. Sylvia sat on Mabel's bed (which Mabel had decorated with pink... well, pink everything) as Mabel pointed at her cheek. "Check out this giant smooch mark he gave me!"

Her cheek was completely red. Dipper let out a loud yell and jumped back. Mabel cracked up. "Ha ha! Gullible. It was just an accident with the leaf blower."

Sylvia waved to catch their attention, and then made questioning motions. "How does one have an accident with a leaf blower??" Dipper guessed, and Sylvia stuck her thumb up in an affirmative motion. "... we have a lot of weird accidents like that," Mabel said slowly, and Sylvia shrugged.

"No, Mabel," Dipper said quickly, returning to the subject at hand, "Listen! I'm trying to say, that maybe Norman isn't what he seems." He held out the journal.

Mabel let out a huge gasp. "You mean he might be a vampire??"

"Guess again, sister. Sha-BAM!!" Dipper showed her a page. Unfortunately, it was the gnomes page.

"Ew!!" Mabel exclaimed, as Sylvia fell off the bed. "Oh! Syl, you okay??"

Sylvia wasn't laughing-- she hadn't laughed in too long to do it now-- but the small smile on her face and the fact that she'd fallen off the bed was the closest she'd come to it in a long time.

"Oh, w-wait, I'm-I'm sorry," Dipper said, flipping back a few pages before quickly showing Mabel the zombie page. "Shabam!"

Mabel sighed, crossing her arms. "A zombie?? That is not funny, Dipper."

"I'm not joking!!" Dipper protested. "It all adds up: the bleeding, the limp... he never blinks! Have you noticed that??" he asked. Not the most compelling argument, Dipper, Sylvia thought, sitting back up.

"Maybe he's blinking when you're blinking!" Mabel reasoned. 

"Mabel, remember what the book said about Gravity Falls? 'Trust no one!'" Dipper protested even more.

Mabel frowned at him. "Well, why can't you trust me, huh? Why can't you trust me??" She popped on a pair of star earrings. "Beep bop!!"

Dipper looked desperate now, and he grabbed his sister. "Mabel, he's gonna eat your brain!"

Mabel shoved him away. "Dipper, listen to me. Norman and I are going on a date at five o'clock, and I'm gonna be adorable, and he's gonna be dreamy--" she pushed him out of the room. Sylvia stood up, eyes widening as Dipper stuttered, "Bu-bu-but--"

"And I'm not gonna let you ruin it with one of your crazy CONSPIRACIES!" she yelled, slamming the door in Dipper's face. Sylvia winced as Mabel stormed back over, crossing her arms with this slightly adorable pout on her face. "Ugh, he's just so annoying sometimes!" Mabel grouched, before smiling at Sylvia. "I'm glad there's ONE normal person here!"

Sylvia shifted her weight uncomfortably. Looking around, she found a notebook, picked it up, and wrote in it, before showing the notebook to Mabel. 'Dipper isn't trying to be annoying-- he's just worried about you,' she wrote in the notebook.

Mabel scoffed. "Are you kidding? He's come up with a bunch of conspiracies before. And he's always been too overprotective sometimes," she sighed, checking herself in the mirror again.

Sylvia frowned before writing something else down. 'He really loves you, you know. You're the only sister he's got,' she noted down.

Mabel frowned again. "... I guess," she said finally, before turning back to the mirror. "Now, should I wear the kitten sweater, or the alpaca sweater?"

Sylvia sighed slightly, knowing any more discussion about this topic would just annoy Mabel, and pointed at the kitten sweater. Mabel grinned and clapped her hands to her cheeks. "Oh my gosh! I know, right?" she asked, pulling on the kitten sweater.

x.X. X.x

Mabel headed out the door. Sylvia sat down next to Dipper on the couch as he rewinded through the footage. He glanced up. "Oh, hey Sylvia," he said, playing through them without exactly looking at them. Sylvia watched them out of interest. "I guess Soos was right. I don't have any real evidence. I guess I can be pretty paranoid sometimes--"

Sylvia suddenly hit his arm. "Ow! Sylvia, what--?" he looked up to see Sylvia frantically gesturing at the rewind button. "Rewind? Okay..." he rewinded a bit until Sylvia pressed the play button. He watched Norman with his arm around Mabel. "I don't see what's so import--" He stopped midsyllable as Norman's hand fell off. Norman furtively looked around and reattached it.

"Oh my gosh!! OH MY GOSH!! MABEL!! We've gotta tell Grunkle Stan!!" Dipper almost shouted, rocking himself out of the seat and rushing out the door. Sylvia jumped up and followed him as he ran over to his Grunkle, who was surrounded by people. She'd hardly made it halfway there before he was suddenly tearing off in the other direction, grabbing her wrist and dragging her along with him in the process. Sylvia nearly landed on her bum but she managed to keep her feet.

"Wendy!!" he yelled. "Wendy, I need the keys to the golf cart so I can save my sister from getting her brains eaten by a zombie!!"

Wendy looked at him plainly, and for a moment Sylvia was positive she was just going to write him off as crazy. Then she tossed him the keys. "Try not to hit any pedestrians," she told him.

Sylvia stared after her with a funny expression on her face. Before she shrugged it off and jumped into the golf cart with Dipper, who took off towards the woods. Soos stopped them before they got too far. "Hey dudes: it's me, Soos. This is for the zombies." He handed Sylvia a shovel. Sylvia nodded, grinned, and stuck her thumb up. Which was her method of a thank you.

"And this is in case you see a pinata," Soos added, handing Dipper a baseball bat. Dipper looked very confused. "... thanks?"

In any case, Dipper and Sylvia drove off, in order to go save Dipper's sister from a zombie.