My sisters husband is a pretty lazy person who spends 10+ hours a day playing video games. They have 2 very young kids and an older kid also. They live at my parents hows and my parents dont know what to do either. Ive been staying with them during quarantine and have seem there relationship now and its pretty sad. My sister takes care of the kids along with my parents and he just stays in a separate guest/game room all day and only comes down to get food and go back up. They dont talk to each other unless its something small and he sleeps in the guest room when they have a big bedroom that is theirs.

Now im not one to get involved with other peoples relationships or what they argue about however I can see no one in the house is happy including my parents and that is the most important thing to me. They have never paid rent to live with them however they do buy groceries. He doesn't do chores or household things without my sister having to tell him to do it. Its like this guy has no drive to take care of his family or even himself. He is overweight and eats like shit and drinks coke and redbull all day. Sleeps in till 11am and then jumps back on the video games.

How do I talk to someone like this and tell him they he needs to step up as a man and also as a human being and take responsibility for his life?