Back before Jeff snapped and killed his family, he and Liu shared a room. This... lead to quite a few arguments, as Jeff was rather fond of staying up till the wee hours of the morning on his phone, and Liu couldn't sleep because of the light.
(Hahahahaha my sister and I are the same way. I'm Jeff on this one, believe it or not, and much like Jeff, when she asks me to turn off my phone I laugh and say no. I'm a horrible sister.)