AN: There was a moment in "The Small Things" that was really important to Dipper, but the reader didn't get to see it since that story was Stan POV. So here's that part perspective flipped for you.
Dipper remembers a time a really long time ago when he was really little, so little that he was still Mason. Mabel had tripped over Mason's favorite dinosaur toy and broke it and hurt her knee. Grandpa Shermie cleaned up her boo-boo and put a band-aid on it and kissed it, but Mabel kept crying and crying because she wanted Mason to kiss it better. Mason didn't want to kiss it better because he was really mad at Mabel for breaking his favorite dinosaur toy, but Grandpa Shermie said he had to. So Mason kissed Mabel's knee on top of her band-aid and Mabel stopped crying and she said sorry to Mason for breaking his favorite dinosaur toy and gave him a hug. Then Mason wasn't mad anymore, because Mabel said she was sorry and also Mason liked hugs from his sister almost as much as his favorite dinosaur toy.
After Mason and Mabel made up, Grandpa Shermie said to them in his serious voice, "Now Mason, I want you to remember that you've got to take care of your sister when she needs you. And you Mabel, you've got to take care of your brother. The two of you are twins, so that means you stick together and watch out for each other, no matter what or how angry you get. Okay?"
"Okay," Mason and Mabel agreed.
"Good. Because if the two of you don't take care of each other, then you might turn around one day and realize you've lost each other, maybe even for good. And I don't ever want that to happen to you." Grandpa Shermie looked really sad when he said that, so Mason and Mabel gave him a hug, and that's as much as Dipper remembers.
Dipper knows he has to take care of Mabel right now because she needs him, except, no matter how much they ask and say please and promise to be good, Aunt Karen won't give Mabel's scarf back. Dipper isn't tall enough to take the scarf out of Aunt Karen's purse, and he thinks Aunt Karen would notice if he tried to get a chair so he can reach. So Dipper will just have to take care of Mabel a different way.
He waits until Aunt Karen is busy talking with some old lady who called Dipper 'Mason,' even though that's not his name any more, and said she was a friend of Grandpa Shermie's. When they aren't looking at Dipper or Mabel anymore, he grabs his sister's hand and starts walking away.
"Where are we going?" Mabel asks.
"To hide from Aunt Karen," Dipper tells her. Mabel nods because it's a good idea because Aunt Karen is mean and they don't want to have to spend time with her.
Dipper finds a door to another room and in that room there's a big cabinet. They decide that's the best hiding place because Aunt Karen probably won't find them in there even if she looks for hours. The inside of the cabinet is dark, but they aren't scared because it's big enough for the both of them, but it's still way too small to fit any monsters. And there aren't any spiders because Dipper, who isn't afraid of spiders because Grandpa Shermie told him that spiders are the good bugs who eat all the other bad bugs, checked for them for Mabel before they crawled in. The cabinet is perfect because it's dark and quiet and safe and there's no Aunt Karen to be mean or take their things.
"We should stay here until Aunt Karen leaves for Alabama, so we don't hafta go with her," Mabel says.
Dipper agrees. He doesn't think it works like that, because he thinks that they're supposed to live with Aunt Karen now and she won't leave until she has them, but it's still a good plan and they should try it.
They sit quietly as they can for a really long time, hoping no one will find them, but then Mabel starts crying again.
"Dipper, I wanna go home. And I want Grandpa Shermie," she says.
Dipper doesn't know what to do. He can't get Grandpa Shermie because Miss Joann says Grandpa Shermie is gone forever just like their mom and dad, and he can't kiss it and make it better because Mabel hurts on the inside in her chest and her tummy, and he can't get her scarf for her to hide her face in like she likes to do when she hurts on the inside because Aunt Karen has it. He doesn't even have a blanket to use instead.
Then Dipper remembers that the suit Miss Joann made him put on his morning has a jacket and a jacket is kinda like a blanket. "I have an idea," Dipper whispers to Mabel. He takes it off and puts it on Mabel's head to hide her face. Dipper hugs her so even though Mabel can't see him she knows he's here taking care of her. "See. Almost as good as Scarf Town." Then the door to the cabinet opens.
Dipper doesn't know if he likes Grunkle Stan. Grunkle Stan did say he was gonna get Mabel's scarf from Aunt Karen, and sometimes grown-ups can make other grown-ups do things that kids can't, and Mabel likes him, which most of the time is enough for Dipper because Dipper is really smart with numbers and words, but Mabel is really smart with people. But Grunkle Stan also made Mabel cry and he has a secret with those funny gloves of his, so Dipper doesn't know.
"Though I got say you're handling this surprisingly well," Grunkle Stan says after Dipper tells him he's a big boy and doesn't need to be carried. People keep saying that stuff to Dipper, Grunkle Stan and Miss Joann and Miss Katy, the lady with Child Protected Services, and he doesn't know why. Dipper isn't doing good, he hurts a lot on the inside and he has lots of feelings that are weird and he doesn't understand and are too big for him. But Mabel's feelings are even bigger than Dipper's and they make her cry all the time, so Dipper has to take care of her.
"Mabel needs me," Dipper says and he glares at Grunkle Stan waiting for him to say that Dipper shouldn't worry about that and he should let the grown-ups take care of them both. Nobody thinks Dipper can take care of Mabel because he's too little and too hurt, but he can. He has to, because he's already lost Grandpa Shermie and he can't lose Mabel too.
Grunkle Stan hugs Dipper sideways and smiles at him. "You're a good kid."
Dipper smiles back and then grabs onto Grunkle Stan and holds him tight. Grunkle Stan doesn't think he's too small or too hurt to take care of Mabel. Grunkle Stan thinks he can take care of Mabel and thinks he's doing a good job taking care of Mabel, and Dipper isn't going to lose his sister too.
Dipper's feelings get even too much bigger until they come right out of his eyes and all over Grunkle Stan's jacket. But that's okay. Because Grunkle Stan knows how important it is for Dipper to take care of Mabel just like Grandpa Shermie did. So Grunkle Stan can make sure that Dipper takes good care of Mabel, and it's probably okay if Dipper even lets Grunkle Stan help take care of Mabel.
And maybe if Dipper is really good and does a really good job of taking care of Mabel, Grunkle Stan and Mabel will help take care of Dipper too.