There's more to Heesoo, the chef than what meets the eye because his intentions towards favouring Yooil aren't really clear. On one hand, he seems to enjoy her admiration of his food unlike the other characters who don't eat the food but mindlessly praise it. But at the same time, he seems a bit obsessed with Mooyi for whatever reason and may just be using her to get to him. I know people suspect him to be the stalker but it really can't be as obvious as the stalker sending food and him being a chef because if so the stalker character is in plain sight. However, it seems to me that he has a hidden vendetta against Mooyi.