You could have guests dress up as their favorite caricature characters. Also, have a caricature artist draw guests' portraits as party favors.
You could have car-shaped cookies and cupcakes. Also, decorate the place with cartoon car posters and balloons.
You could have a caricature drawn of the birthday person as their favorite superhero. That would be a unique and fun surprise!
Another idea is to make a caricature of them in a funny situation, like getting stuck in a giant cake or being chased by balloons. It adds a lot of humor to the drawing.
You could have a theme like superhero caricatures and have everyone dress up as their favorite superhero. Or have a caricature artist on-site to draw guests as funny animals!
You could have a superhero-themed party with everyone dressing up as their favorite comic heroes. Also, decorate the place with comic book covers and serve treats shaped like comic characters.
You could have characters dressed up as superheroes or princesses. Or maybe show a cake with candles that look like they're about to blow out.
You could have a cake shaped like a favorite cartoon character or with images of cartoon animals on it.
For a 1920s themed party, a wife could wear a flapper dress. It was a symbol of the women's liberation movement of that era. The dress is usually short, with lots of fringe and beading, and paired with a long string of pearls and a headband with a feather.
You could have a race car-themed party with checkered flags and toy cars as decorations. Serve food in car-shaped containers!
Well, you could include a 'Capture the Flag' game like they have at Camp Half - Blood. It would be exciting for the characters in the fanfiction. Also, for the party decorations, having floating Greek columns made of cardboard and painted to look like marble would be really cool. And don't forget about a 'prophecy - writing' station where guests can create their own prophecies, just like in the books.