Who is Giovanni and Dario from Eat, Pray, Love: One Woman's Search for Everything Across Italy, India, and Indonesia and what is their importance?

Elizabeth Gilbert's first "Tandem Exchange Partner" in Rome during the first leg of her travels, Giovanni at 25 is ten years younger and has "giant brown liquid-center Italian eyes" that tempt Liz to give up temporary celibacy. They meet after Liz answers his Internet ad for a partner to practice Italian while he practices English.