She takes it, gingerly.

"It's for me?"

"'Course it's for you," he says warmly.  "It's your birthday, isn't it?"

Shy smile.

She opens the box.

Cake!  Chocolate frosted cake with "Happy Birthday Harriet!" written on it in blue icing.

And clearly the adult wants her to eat it...

She doesn't have utensils and forgets briefly that she needs them. She swipes her finger through some of the frosting, tasting it.

The giant chuckles fondly at her.  "Sure I got a fork here somewhere," he says, "but don't let that stop you on my account."  (He does start patting his pockets vaguely, just in case she lets it stop her anyway.)

She hesitates. (An adult saying it's okay to break the rules is always kinda stressful...)

He produces a knife and fork from one of his many pockets and frowns at them speculatively.

"Need to take this back for a mo'," he says, and snaps his umbrella closed.  He taps it gingerly against them once or twice, and they get a bit shinier.  He re-umbrellas her and hands over the silverware.

She... Sits down to eat?

"Could sit in the boat, if you like," he says.  "Should be heading out soon anyway."

"Uh. Okay." She gets up, awkwardly, and walks over to the boat. (It looks kinda unsteady...)

He climbs in after her; the boat creaks and wobbles a little.

"Oi," he says, and raps his knuckles against the side of the boat.  "Steady on."

The boat stops rocking.  It's quite steady now, in fact.

He taps his umbrella against the seat she took, and it dries off and warms a little; and he re-umbrellas her again.

"...Is the boat magic?"

He pats it fondly.  "Sails all on her own.  Belongs to Hogwarts."

"How's it work?"

"Powerful wizards can enchant objects to work on their own and do as they're told," the man says.  "Don't understand it much better than that, if I'm honest."

"Does Hogwarts teach about that?"

"The basics," the man says.  "But nothing really fancy until you're N.E.W.T. level - that's after fifth year.  And to make something like this you'd have to study on your own after Hogwarts, or find a tutor."

"Are there magic universities?"

"Some jobs have people that'll train you up for 'em after you graduate Hogwarts," he says.  "But mostly wizards who want to keep learning after N.E.W.T.s have to find people looking for apprentices."

"...Oh..."

"What's wrong?" he asks.

"Don't think people'll want me as an apprentice..."

"I don't believe it," the man says.  "If your mum and dad are anything to go on, you'll be a fine old wizard when you grow up.  Just 'cuz those Dursleys have it in for you don't mean anyone else is gonna be like that."

"...But I'm not my parents..."