Despite being the oldest, Boy is more sensitive and sometimes more childish than Girl, who, by contrast, usually acts more her age. Girls typically tend to mature earlier than boys.
Why is Cheese, the more feminine and cute-looking of the three girls and the youngest of the six, the meanest of the group? Part of it stems from the fact that eating too much cheese could lead to constipation and other health problems. Another reason is due to the fact that she's a child. It is also possible that Cheese's Spoiled Brat nature stems from living with the people she has as her family members - Mom possibly spoiling her a lot and not having to discipline her much while also having to work a lot to have time for her, Cat being too scatterbrained and minding her own business, and Girl's irresponsible, sardonic, and at times manipulative plus the fact that she frequently uses her phone a lot, implying that many of Cheese's negative qualities stem from years of living with Girl. The fact that the three do absolutely nothing to try to fix her behavior is partly why Cheese tends to be mean, sometimes to the point where she gets off scot-free for her misdeeds.
As humiliating as the experience was for her, there are several other factors as to why Cheese's Cheese Ball going awry in addition to her siblings botching their assigned tasks and Stevie and Susie mocking her party:
When Cheese announces to the others of her party, Mouse tells her that he's been preoccupied with a few of his projects while Girl explains to her that they couldn't get her parties perfect 100% all the time and that they all have lives. Despite this, Cheese still insisted that they celebrated anyways.
There was also the assignments for each of the party events. Boy was given slide duty, which resulted in a poorly made wooden see-saw instead, when Mouse, the Gadgeteer Genius of the bunch, would actually be able to excel in making a spectacular slide that would impress Cheese. Dog was assigned to make the buffet, which resulted in him improvising by using leftovers and random garbage, when such a task would be Boy's specialty given that certain episodes emphasizes his impeccable cooking skills. Girl's job was to make a fancy dress for Cheese to wear at the party, resulting in Cheese wearing a frog-looking costume made from random cosplay items and a jetpack. Cheese has plenty of dresses she could have worn instead, even maybe one from her previous Cheese Balls. All Mouse had to do was make a piñata and put candy and prizes inside it, only to hang an empty cardboard box instead. Cat was tasked to hand the invitations but misinterpreted what Cheese told her and only invited Stevie and Susie. Given how clumsy she can be at times, Cat probably should've been left out of the party planning to avoid causing issues while piñata making and invitations could've gone to Girl or Dog. While it may seem like the others were lousy at their tasks and had little effort in trying to make the party great, it is also due to Cheese having given them the wrong assignments that they failed her.
When showing Cheese the slide they made and had the Smiths ride all the way down to humiliate them, none of the others thought of taking off the costume Cheese had on before going back to the backyard. Come the end of the episode, Dog accidentally triggers the jetpack Cheese had on, launching her all the way to the slide where she ends up enduring the same humiliation her siblings tricked the Smiths into enduring.
Most importantly, considering the typeofindividual Cheese is, her ruined party could essentially be karma for all the mean things she's done in her life. The Cheese Ball going awry isn't just from her siblings and rivals ruining her special day, but also a much needed slap in the face onto Cheese's ego as well as her arrogance and short-sighted party planning skills.
Dog and Lady Burlington bond in "Suit Yourself", yet later episodes don't acknowledge that dynamic whatsoever. In Dog's case, he's never one to take advantage of others and only agreed to join in on the luxury because Lady Burlington offered to and that he enjoyed hanging out with her that day. In Lady Burlington's case, it's possible that due to her wealth and being one of the most important people in the town, she has plenty of important responsibilities to tend to, so while she still remembers Dog and his siblings, she might've forgotten about their bond because of her obligations. Cat, by contrast, tends to come by Lady Burlington's mansion to receive affection and be fed kitty treats, specifically in "Cat Burglar". Cat's frequent visits plus the rare amount of times she's helped her could be why Lady Burlington acknowledges her more, to the point where Cat is on the list for one of her parties in "Fix it Yourself".
In "Staycation", Cheese had been wanting to go to Posh Daintybottom's movie premiere all day with her main issue stemming from having to put up with her family's staycation since the RV broke down before they could go to Melody Lake. After the Smiths rat her out to the others, who get mad at Cheese for her lies and decide to leave her be so she could go to the premiere, Cheese ultimately decides to apologize and join her family in the end instead. Had Cheese went to the premiere instead, she would've not only risk spending the whole event guilty and upset for lying to the others but also have to put up with Stevie and Susie all by herself. So as painful as it would be for Cheese to miss the event, she ultimately decided that patching things with her family was more important at the moment.
