Condition: Must have completed No ink now!
After completing No ink now!, go through any portal then go back and talk to the picture vendor. He will tell you that he is in love with Xaohui, the daughter of the hotel owner in Chang'an. You will get a portrait of Xaohui to show to her.
Go to the hotel and show the picture to Xaohui. After a short conversation, the father will overhear and will allow the picture vendor to propose to Xaohui.
Go back to picture vendor to tell him the news and have the option to pay 5,000 to help for the wedding. Help him and receive reward.
Reward: Riddle Paper*20, Forgotten Scroll*1