"Boy!" his Aunt Petunia yells, banging on the door of his cupboard. 

"Yes, Aunt Petunia." Bruce checks the cupboard door for spiders, opens it, and rolls off his mattress to stand up in the doorway, bumping his elbow on the way out. He's mostly elbows, at least the parts of him that aren't knees, but it's hard to be sure under the oversized hand-me-downs. Now, what does his aunt want? Probably for him to cook something, given the time of day, though given that it's Dudley's birthday it could be something unusual instead.

She wants him to cook this here bacon while she fusses over his cousin. 

Yup, he'll cook that there bacon. If she fusses intensely enough he can even break a bit off the end of this piece and a bit off the end of that piece and eat them without her noticing. They're hot enough to burn so he just swallows them with the minimum possible amount of tongue involvement.

She fusses pretty intensely at Dudley, who throws a tantrum at receiving one less present than last year and is placated by Vernon promising him two more. 

...It transpires that Mrs. Figg, Bruce's usual babysitter, has tripped over one of her many cats and broken something. And the backup is on vacation. 

Gosh. Poor Mrs. Figg. For that matter, poor cat. Maybe they'll take him to the zoo and leave him in the car and he'll get to explore a parking lot. Maybe he can get one more bit of bacon while they figure it out . . . Nah, better not risk it, they keep shooting him glances.

Eventually it is decided that they have no choice to bring him along. And not leave him alone in the car, that's a nice car, they can't trust him with it. Dudley attempts to throw a tantrum over this but is interrupted by the arrival of a friend he wants to look cool in front of. 

Oh wow Bruce is gonna go to the zoo! That's super great. He doesn't let how super great it is show on his face in case they change their minds. He says "Yes, Uncle Vernon" in his most neutral voice, the one that suggests he isn't going to do anything whatsoever and in fact probably doesn't exist and should just be ignored.

(Dudley's desire to look cool is not one that can be solved by his parents handing him something, and thus will have to go unfulfilled. Hopefully Dudley will not notice this.)

Piers Polkiss is as much of an asshat as Dudley and does not seem to notice how uncool the latter is. 

The zoo is great. The ice-cream lady asks him what he wants before Aunt Petunia can shuffle him away. 

Eep. "I-I'd like a strawberry bar? If that's alright?"

She gives him one with a smile, and Aunt Petunia pays for it with a minimum of grumbling. 

Later, Dudley kicks up a fuss about there not being enough ice cream in his Knickerbocker Glory, so Aunt Petunia gets him a new one. Bruce is allowed to finish the first. 

Holy cow, double ice cream! And the zoo is full of neat animals! Dudley's birthday is turning out way better for him than his own ever does, which means Dudley has actually done something nice for him by proxy. If Dudley notices this fact he'll definitely take it out on Bruce later, but Bruce is a pretty good runner and Dudley usually can't catch him until he's too worn out for effective violence. Piers is faster, though, so Bruce is going to be extra watchful until he goes home.

And now for the reptile house. 

Dudley attempts to bother a snake. The snake, unlike Bruce, does not have to live in the same house as Dudley and does not have to acknowledge that he exists. 

Wow, reptiles! Actually he's pretty sure some of them are amphibians. He reads all the little explanatory plaques and determines that yes, reptile house is a bit of a misnomer but all the species are clearly labeled.

That snake looks as zoned out as Bruce usually feels. He wanders over to it once Dudley isn't looking. "I bet you don't like being cooped up in there, do you?" he murmurs.

The snake raises its head to look at Bruce, then gives a soft side-to-side flick of its head. 

"Did that snake just understand me" collides with "is someone voluntarily having a conversation with me" and Bruce runs out of brain to be surprised with. He ends up saying, "That's too bad. I hope they at least feed you plenty. They ought to, you're useful."

The snake nods. 

"That's good. Still, I bet you'd rather be in . . . " he checks the explanatory plaque, "Brazil or somewhere." Sure, apparently the snake was born in the zoo, but Bruce doesn't remember anything before the Dursleys and still knows enough to wish things were different.

The snake nods again. 

Bruce leans against the glass, contemplating the unfairness of this situation--then jumps back in startlement as the glass disappears and ends up in a heap on the floor.

The snake looks up at him, hisses "Thanks," and slithers off, to a chorus of screams from other zoo-goers. 

This is not actually the weirdest thing Bruce has ever experienced. It is, however, the weirdest thing he has experienced recently enough that he hasn't started doubting his memory of it yet. It takes him a minute to remember that he needs to get somewhere else in the exhibit pronto so nobody realizes this was his fault. No siree, he had nothing to do with this, he was just standing here looking at the chameleon the whole time. 

His Aunt Petunia and Uncle Vernon Are Not Buying It. Of course, so as to avoid any association with abnormality, they refrain from expressing this in front of Piers or anyone else, but once they get home, he's confined to his cupboard for a while. 

Yeah, he figured. It was worth a shot though. Time to lie in bed in his cupboard and calculate the squares and cubes of increasingly large numbers until he falls asleep from hunger and/or boredom, then wake up and repeat.

Eventually, summer rolls around. Eventually, they let him out.