The Lightning Thief is definitely alive, as Percy Jackson and the Olympians creator Rick Riordan and wife Becky share their favorite line from the book that made it to the series, as their interview for ComicBook.com shows.

Both Rick and Becky said that their favorite is the one in episode eight. If you haven't read the book, since there are only two episodes available for now on Disney+, be warned SPOILERS AHEAD.

“The sea does not like to be restrained.”

This was something Poseidon (Toby Stephens) said to his son Percy (Walker Scobell) towards the end of the book. (I haven't seen the eighth episode either, but I have read the book.) It's also the first time that father and son meet.

They were discussing Kronos awakening. Poseidon tells Percy not to discuss it anymore because Zeus has forbidden it. Percy wants to argue, but stops himself in time, reminding himself that it would not do to “anger the only god who I had on my side.”

When he says, “As you wish, Father,” Poseidon smiles and asks him, “Obedience does not come naturally to you, does it?”

After Percy says no, this is when he utters that line, “I must take some blame for that. The sea does not like to be restrained.” While it's fitting that the god of the sea says it, it also brings a measure of comfort to Percy as his father acknowledges him for the first time.

But it isn't the last time that line is said. At the end of The Lightning Thief, Percy says it to himself as he promises his father that he come back to Camp Half-Blood. That he now accepts this new part of him: as a demi-god.