What is a theme that connects the myth of Cronus and Rick Riordan's The Lighting Thief?

One of the central themes in Rick Riordan's The Lightning Thief concerns the underestimation of one's values and strength. Just like Percy's abilities were underestimated, especially at the beginning of the book, the threat Cronos, or Kronos, poses and his power is underestimated by the end of the book.At the start of the book, Percy struggleswith school because he has been diagnosed with ADHD and dyslexia; plus, he is in general...

One of the central themes in Rick Riordan's The Lightning Thief concerns the underestimation of one's values and strength. Just like Percy's abilities were underestimated, especially at the beginning of the book, the threat Cronos, or Kronos, poses and his power is underestimated by the end of the book.

At the start of the book, Percy struggles with school because he has been diagnosed with ADHD and dyslexia; plus, he is in general considered to be a juvenile delinquent. However, as the book progresses, we learn that Percy is actually a demigod whose father is Poseidon. As the book further progresses, we learn he has hidden abilities to think of solutions to problems on his feet, and together with Annabeth and Grover, Percy is able to find the master lightning bolt that had been stolen from Zeus and rescue the world from a war between the gods. More importantly, he discovers that it was Kronos who stole the master bolt by using the demigod Luke as an agent; Kronos further used the war god Ares as an agent to start a war between the gods.

Even before Percy makes the above discovery, he realizes that others were underestimating the powers of Kronos. According to the myth, Kronos was overthrown by his son Zeus, who used the master bolt to fling him from this throne, cut him up into bits, and fling those bits to the pit of Tartarus (Ch. 21). When Perseus tells Zeus and Poseidon about his belief Kronos used Luke and Ares to steal the master bolt and start a war between the gods, both Zeus and Poseidon reject the idea. When Perseus further argues that Kronos is healing and regaining his powers, Poseidon replies with the following:

From time to time, over the eons, Kronos has stirred. He enters men's nightmares and breathes evil thoughts. He wakens restless monsters from the depths. But to suggest he could rise from the pit is another thing. (Ch. 21)

Yet, Percy learns through his encounter with Luke in the woods that Kronos is becoming capable of far more power than Zeus and Poseidon are willing to admit. Therefore, Zeus and Poseidon are underestimating Kronos's powers, which can lead to disaster in the form of worldwide destruction. Hence, all in all, the novel makes use of the Kronos myth to show the dangers and consequences of underestimating strengths and values.