Based on the predebut picture of Jongdae and Yixing pouring over a book together.  

"What are you doing?" Yifan asked.

Jongdae's eyes flew open. "I was doing my Mandarin homework."

Yifan frowned at him. "You're not going to learn anything with your eyes closed Jongdae-ah."

"I was concentrating." Jongdae insisted.

All Yifan did was hum unconvincingly before beginning his nightly beauty regime.

Jongdae sighed and began looking at the characters all over again. Ever since they got their new roommate arrangement he had been spending less and less time with Yixing and that meant he was falling behind in his Mandarin. He knew he could just go into Luhan and Yixing's shared room and ask for help but he didn't want to bother them. It was a lot easier when they were roommates because Yixing would just offer to help him every night and wouldn't take no for an answer. Jongdae missed Yixing. He knew he could ask Yifan for help but Yifan didn't have the patience that Yixing had or the comforting and encouraging mannerism.

He closed his eyes again and pictured Yixing's warm body next to his, the feel of his hand on his back, ghost fingers dipping in different places on his back with the each different tone. He pictured Yixing pronouncing the specific words slowly, in that slight accent he had,  and the way his lips would move as he did so. Jongdae sighed again, this was going to be a long night.

There was a knock at the door making Yifan grunt in response. The person behind the door must've taken that as a consent to enter as the door opened and a head popped in the through the doorway. Jongdae glanced up to see Luhan.

"Jongdae, Yixing's waiting for you in the living room. He told me to tell you to bring your Mandarin stuff." Luhan said.

Jongdae blinked at him for a few seconds before scrambling to gather all his work and rush to the living room. Yixing was lounging on the sofa in a thin vest and boxers. He gave Jongdae a lazy smile before patting a place next to him. Jongdae smiled at him as he settled down and drop his work in front of them.

Yixing hooked an arm around Jongdae's waist and pulled him closer. "Now, where were we last?"