Hobbes, being a cat and much taller than Calvin besides, has the advantage in many areas; the most insignificant of them not the fact that he can scale the living room bookshelf quite easily and enjoy relative peace and quiet there - peace, at least, for a certain value, if not so quiet when Calvin is standing on the floor at the foot of the shelf yelling for him to get down. Hobbes has practice at ostentatiously ignoring the kid anyway, when Calvin deserves it.
"Hey!" Calvin yells up at him, persistent. "Hey, Hobbes! Come down already! C'mon!"
Hobbes stretches, arching his stripy back luxuriantly, and then curls up a little tighter.
"Hobbes! Hobbes! C'mon! Just do what I say!"
By the time Calvin has destroyed half the living room dragging in the ladder from the garage, his parents are home, and Hobbes can pull a smug face at his best friend behind Calvin's mothers' back while she scolds.
Even best friends are enemies sometimes, but when things are serious they've got to be there for each other. Calvin is lucky, sorta; he's got a tiger on his side, and a best friend he can fit into his backpack and carry to school. He does it, too, even when this tendency strides well into the realm of weird and the other kids notice and start to make fun.
Hobbes curls up in Calvin's backpack, eats the tuna sandwich Calvin stashed there for him, listening to (and eventually tuning out) the teacher talking about the vagaries of addition. He's not thinking about much, not really, until Calvin bends down with the pretense of getting his pencil sharpener out of his back and whispers "Buddy, your tail is showing."
"Right," Hobbes whispers back, and takes a moment to pull the offending appendage back into the bag. It's not as comfortable with his tail not being allowed to swish and orange-and-black stroke across the floor, but school is school, school has rules, and school doesn't allow tigers. Not even the friendly ones.
It's such a human thing, Hobbes thinks. This is not how tigers would do things.
Above him Calvin sighs and swings his feet, one of his shoes pressing briefly against the bag. Hobbes finishes off his sandwich and licks fish off of his whiskers, closing his eyes to nap his way through the doldrums before recess.
House rules are for a bath every night, washing your hands before dinner, a bedtime at ten (although Calvin doesn't always listen, obviously). But these rules are ones that Hobbes, at least, can get behind. "I don't want to share a bed with anyone who smells like you do before you wash."
"I don't want to share a bed with someone who washes himself with his spit."
"I was in the washing machine just today." Hobbes turns up his nose. "You're in your washing machine now. It's fair."
Sullenly Calvin recedes into the mounds of soap bubbles, until they close wetly over the top of his head, like he's a soapy little treasure being shut into a chest made of clouds.
G.R.O.S.S. is meant to be a democracy, but this is harder to enforce than you might think, especially since there are only two of them, and if they disagree with each other they each only have one vote, and then the tie has to be settled with a fistfight. The rickety tree house can take a surprising amount of abuse while they roll and pummel each other, even as it sheds wood chips and the occasional dried leaf is dislodged from the tree above, floating languidly down to be crunched up into bits, a casualty of battle. Hobbes is bigger, which gives him an advantage, but Calvin is admittedly pretty fierce - it makes a tiger proud.
"I can't believe you want to invite Susie up here, she's a girl -"
"She's a choice dame!"
"That is COMPLETELY against our policy -"
"She smells better than you do!"
Hobbes gets his best friend in a headlock and scrubs at the kid's scalp with his knuckles. Calvin's face is burnt red exertion. He howls like a fire engine until Hobbes lets go to cover his ears, and then they're back to it in an instant.
The whole thing would be a lot easier if Susie was there to act as a tiebreaker (which Hobbes would argue, if they were still just arguing), but they'll both have forgotten what they were fighting about by the time the whole thing is over.
Hobbes doesn't care much for human dictatorships, but he does think they get a lot more done.