Persian Nights: Sands of Wonders

There are points in the game when you will see that Darius has a chat bubble over his head with blinking dots in it, signaling that he has new dialogue for you. For this achievement, you simply need to talk to him once when you see this chat bubble appear and exhaust his dialogue.

The first opportunity you will have to speak to him and earn this achievement is near the start of the game, shortly after meeting him. In the Antechamber, you will need to light the chamber up with a torch as part of the story progression. After the chamber is lit up, you will see Darius sitting on the floor with the chat bubble:

Click on Darius and exhaust both of his dialogue options:

Once you have talked to him about both topics, achievement unlocked! :)