Since this is a fanfiction piece, it was written as if people would know the characters, so first of all my sincere apologies. As there are people who seem to be interested in the story without knowing the original story behind it, I will do my best to make an introduction to the characters and their situation. I will reply first to you here, in the comments section, and I will see what I can do to properly explain the entire setup.
That being said, in the original story, things are as follows. Mo Guan Shan is a bit of a punk and gets into a nasty fight with one of He Tian's friends. Things end with that guy in the hospital, but Mo Guan Shan doesn't exactly escape unpunished. After the fight, a few days later, He Tian finds Mo Guan Shan as he exits a supermarket, while musing over how much he hates to eat packaged meals. For reasons that are not yet clear in the original story, He Tian lives on his own, in a vast loft apartment with very little furniture inside. Hence, he has no one to cook for him.
It is made obvious, at some point, to the readers that Mo Guan Shan's family had a restaurant, so Momo knows how to cook and He Tian is aware of that. So, that day, he grabs Mo Guan Shan and drags him home so the guy can cook for him. Momo is a bit afraid of He Tian, so he obeys. As the story in the comics progresses, the readers witness how He Tian saves Mo Guan Shan from becoming a drop out. He Tian also seems to enjoy Momo's services very much and not only. However, since he doesn't want to humiliate the boy by paying him to be his 'maid', he finds work for Mo Guan Shan at one of his family's friends.
There is quite a bit of drama there, as Momo's father is in jail, and we're not told what for, and Momo acts like a punk because he feels angered and helpless about what happened with his dad. He Tian basically tries - and succeeds so far in the original story - to save Momo from a life of crime.
I hope this clarifies the entire situation a little. If not, feel free to ask more questions!
Thank you for reading!