FFX-2: Good Listener Achievement
FFX-2: Good Listener10
Listen to all of Maechen's stories
You will have the opportunity of four encounters with Maechen during the game. It is very important that you do not press ANY buttons after you speak with him as this will interrupt his story. You must let all his dialogue complete to earn this achievement. You will find him at the Youth League HQ in Mushroom Rock Road (Chapter 1), Logos' Room in Guadosalam (Chapter 3), Celsius' Bridge after the concert (Chapter 4), and Zanarkand Ruins (Chapter 5).
All of these interactions are covered in the 100% Walkthrough, so be sure to follow that so you don't miss anything.