When Rosalyn first comes in as his babysitter she sits down and nonchalantly asks if he has any weed. He looks at her like she's insane and says "No...of course not."
Whether or not this happens in the same day as when Calvin puts away the boxes and is told by Hobbes not to visit the attic, or the next day (or some other one) will be decided later.
The doorbell is ringing. It's ringing constantly, someone is very impatient, and interrupts the rings with knocks. Calvin and Hobbes are interrupted from whatever mischief they're up to (probably the "Queen of France" conversation with Calvin dressed up serves as the segue here, so Calvin is wearing one of Angela's gowns as a costume).
Calvin goes up to the front door, perhaps having to lean up or stand on something to see through the peep-hole.
Hobbes (from the bottom of the stairs, curious at the sudden interruption): Who is it?
Calvin (turning back, afraid): It's some girl!
Hobbes: Well, let her in.
Dialogue is kind of weak here and needs revision. Also when Calvin glances through the peephole
Calvin: What are you insane? What if she's a serial killer?!
Hobbes (frowning): I'm sure she's perfectly safe. She probably here for Angela or Thomas, just tell her they aren't home.
Calvin: You do it!
Hobbes: It's your house!
Calvin: It's not like I own the mortgage!
Hobbes: Why are you acting like such a wuss all of a sudden?
Calvin: You know I don't do well with strangers!
Calvin (quickly glancing at the peephole and back to Hobbes): Listen, we'll just ignore her okay? Act like nobody's home.
Rosalyn (behind the door, between knocks, annoyed): Uh, hello? I can hear shuffling around back there. Can you open the door?
Calvin (panicked): Fuck!
Hobbes rolls his eyes and strolls over, casually pushing Calvin out of the way (although the boy protests) as he opens the door a crack. We cut to Rosalyn's perspective, a paw comes out, holding the door open just a bit, and we see a slither of Hobbes' face (the door is only widened enough to show one of his eyes).
Hobbes (squinting from the sunlight): Uh...yes, can I help you?
Rosalyn: Are you Calvin Ferraro?
Calvin (huddled in behind the wall adjacent to the door, panicked, to Hobbes): What does she want?!
Hobbes looks back at Calvin and gives him a bewildered shrug.
Calvin: Well her she's got the wrong house!
Hobbes (turning back to Rosalyn): Uh... No.
Hobbes: No. I'm not Calvin Ferraro. I think you must have the wrong house.
Rosalyn (looking down at her phone): Really? Because the woman who hired me said I was looking for ten year old blond white male named Calvin Ferraro who lives at "3227 East Quivira Drive."
Hobbes: Ah, well, I think 3227 is actually the next house over.
Rosalyn (pointing): What about that?
Hobbes turns his head and the numbers '3227' for the street address embedded on the front of the house right next to his head.
Hobbes (subtly cringing, turning back): It's a typographical error. Our neighbors have it too. We get these mix ups all the time...
Rosalyn: Because you're not Calvin Ferraro?
Hobbes (unconfident smile): Exactly.
Rosalyn: So who are you then?
Hobbes: Uh... Not... Calvin Ferraro?
Rosalyn pushes the door open, but instead of knocking Hobbes out of the way with a shout it is Calvin she knocks back as the pair abruptly switch positions. Shaking off the disorientation from the sudden shift, Calvin scurries back to the cover of the stairs while Hobbes glares daggers at the intruder.
Rosalyn (casually shutting the door behind her as she takes a few steps into the foyer, looking around in awe): Holy shit, this place is off the hook...
Calvin (yelling from behind the cover of the stairs): Hey you can't just barge in like that I'm gonna call the cops!
Rosalyn (putting her backpack down): To tell them what, your babysitter has arrived?
Calvin (still behind the stairs): Angela wouldn't hire a babysitter!
Hobbes: Yeah, Angela wouldn't hire a babysitter!
Rosalyn (cocking her head as she creeps a little to the right, trying to get at an angle to see the boy behind the stairs): I heard you the first time. Why don't you come out from back there? I don't bite.
Rosalyn kneels like she's trying to coax a stray cat. Calvin peeks his head out to steal a glance and quickly pulls back.
Rosalyn: Your mom said you were shy.
Calvin (still hidden): She's not my mom! And Angela wouldn't hire a babysitter!
Rosalyn (bored of trying to get Calvin to come out, roaming through the house curiously): I guess she didn't want you to be alone...
As Rosalyn studies the art on the walls and flicks a few of the knick-knacks she seems completely unaware that Hobbes is also following her, staring daggers. She roams out of sight and Calvin can hear her rummaging through the pantry.
Calvin (yelling): You're not supposed to be in there!
Rosalyn (off-camera, yelling): Your folks must be loaded!
Calvin (yelling): We don't have a lot of money, and they're not my folks!
There's no reply and Calvin can't see into the kitchen from this position on the stairs. His curiosity getting the better of him, he creeps out, huddling behind a wall as he turns a corner to peek inside. But the kitchen is empty.
Rosalyn (off-camera): So...
Calvin jumps back, she's behind him, holding a bottle of scotch she found. She came back around the other way.
Rosalyn (cont'd): How'd that happen?
Calvin glances her up and down nervously, but he's out in the open now. He notices the bottle of scotch she has and points at it.
Calvin: Hey that belongs to Thomas!
Rosalyn: Oh, my mistake...
Rosalyn proceed to unscrew the cap and take a shot anyway.
Rosalyn (wincing a bit): "Thomas" needs to get better taste.
Rosalyn (cont'd, turning to Calvin): You guys got any weed?
Calvin (nonplussed): No...
Rosalyn (shrugging): Worth a shot...
Calvin just watches in confusion as she takes another gulp of the bottle. Hobbes is also watching with his arms crossed, somewhat impressed.
Hobbes: You...haven't done this much, have you?
Rosalyn (wiping away some tears forming in her eye, nonchalant): I'll admit this is my first gig. But worry not, I'm an expert on children. I raised my mother for nineteen years.
Rosalyn (setting the scotch on the counter, holding out her hand with a smile): My name's Rosalyn.
Calvin (still shy): ...Calvin.
Calvin replies but doesn't shake hands and Rosalyn raises an eyebrow and raises her hand slightly in an inviting gesture. Calvin makes eye contact with Hobbes before reluctantly shaking hands but as he does Rosalyn pulls his hand back to her, her other hand reaching to pull the sleeves of his shirt back, revealing the scars running across his arms (she previously only saw the tip on his palm).
Rosalyn (creepy grin): Wicked!
Calvin pulls his arm back quickly, covering it once with the shirt sleeve once-more, clearly uncomfortable. Rosalyn just watches dispassionately.
Rosalyn: Those are some mean looking scars for a kid your age. Do the other ones go across your whole arm too?
Hobbes (noting to Calvin): She's observant.
Calvin (sort of recoiling, standing his distance like someone's about to try to beat him up, reluctantly answering Rosalyn): It was an accident...
Rosalyn: Is that why you don't live with your parents? Because they cut you?
Calvin (assertive): Nobody cut me.
Rosalyn (curious, flippant): So you cut yourself then?
Hobbes (still in the same position behind with his arms crossed, speaking on Calvin's behalf as he often does, assertive in his lower voice): That's none of your business, Rosalyn.
Rosalyn seems somewhat surprised by the response, but she falls silent and when she next speaks her flippant attitude has become much more serious.
Rosalyn: Should I call CPS?
Calvin (surprised): What? No!
Rosalyn: Listen kid, if somebody's hurting you...
***Does Calvin yell at Hobbes "Hobbes I want you to maul this motherfucker!" here? Kind of a little too silly and I don't know how Hobbes would respond, maybe Calvin doesn't even run to the stairs but just pulls back quickly and
I'm thinking maybe whens he explains she's a babysitter she holds out a business card to him that has something comically creepy on it. Maybe she does this when she first explains she's a babysitter, or when she introduces herself.
Maybe Hobbes makes some comment to the effect that Calvin's not a baby.
At some point she says he's pretty cute when he's not hiding / she can see his face.
At one point Calvin gets annoyed at her misunderstanding, asserting "This is my house!" and explaining it belonged to his mother and now it belongs to him, leading Rosalyn to ask what happened to his mom.