Percy J. == Harry P. for retards

A cursory comparison of the Harry Potter series with the Percy Jackson & the Olympians one shows that the latter is a "cheap plastic imitation" of the former.

They have much in common: set in the modern world, they modify it to contain magic (as spells and potions or ancient Greek gods); the narrative centers around a single boy with a doomsday prophecy hanging over his head; each book covers one year of his life.

The differences, however, amount to the opposite recommendation: "encourage your kid to read it" vs. "waste of time".

As mentioned above, both are centered around a single boy; the reader only knows what he knows and when he knows it (with a few trivial exceptions like conversations between the Minister of Magic with the muggle Prime Minister in the Potter series). However, the Potter series are told in the third person, which allows the author to use an excellent language with a rich vocabulary, while the Percy series is in the first person, narrated by a "dyslexic kid with an ADHD" (alas, this is no Huckleberry Finn), with hardly a single word above the grade level.

Percy is choke full of action to the degree that it becomes dull and repetitive, there is nothing mundane there; Harry is easier to relate to - he does homework and faces other ordinary day-to-day chores.

Percy is highly predictable; if you are familiar with the Greek myths, you can usually guess what is coming just from the names of the characters. Harry's adventures are more imaginative.

Percy lives in the world of girls: there are hardly any boys there "with a speaking part" (Luke early in the narrative, Nico later; note that Grover and Tyson are not humans and thus are hardly relevant) and plenty of girls which makes for a rather primitive "romantic line". Harry's world is much larger, with many different ages and both sexes amply represented for an engaging "romantic line".

Percy's world is black-and-white, with everyone being either a friend or an enemy; Harry lives in a world with just one arch-villain and no saints, people being reasonably flawed in various aspects in to various degrees.