Grand Theft Auto IV

As the description says, complete the mission "That Special Someone", this video shows you how:

This is one of the last missions in the game, the United Liberty paper calls you and tells you that they brought the man you were looking for, Darko Brevice into the country. Pick up Roman and drive to the waypoint. Either kill Darko or leave him and take Roman back to his place. After the cutscene where you drop him off, the achievement will pop up.