They're both korean BL dramas, with serious topics, characters who really have a background, a reason to act like they're doing !!
I fall in love with both cinematography, i admit, they both made me cry, so if you want a serious BL, but also sad, you can watch those <3

They both have Lee Jae Bin as a main actor (lead couple) & they're both korean BL !!
Even if Choco Milk Shake is less serious, with a topic more joyful and calm, Gray Shelter is following the path of a BL with well written characters, sad backgrounds, and (to me), realistic characters, with real behaviors