The last I saw of Percy and Annabeth, their Prius was turning the corner on First Avenue, Percy singing along with Led Zeppelin on the radio, Annabeth laughing at his bad voice. Alex crossed his arms. If those two were any cuter together, they'd cause a nuclear explosion of cuteness and destroy the Eastern Seaboard.
The narrator reflects on a memorable moment with Percy and Annabeth, observing them as they drive away in their Prius. Percy is joyfully singing along to Led Zeppelin, while Annabeth laughs at his off-key performance, capturing a sweet and playful scene between the two characters.
Alex humorously notes that the bond between Percy and Annabeth is so adorable that it could be deemed hazardous, implying that their cuteness is overwhelming. The description highlights the strong chemistry and affection between the couple, adding depth to their relationship in the story.