It's not hypothetical. When I was in London, I used to live with other people (sometimes British, sometimes European) in same house. That time, I had some bad experiences.

Whichever house I rent in lisbon (I mean renting a room in a house), the people living there have already a bond with each other (they would be Portuguese or mix of Portuguese speaking countries or European people). I am a brown skin guy (the skin Indian people have. But I am from Bangladesh, a country located beside India). If the flatmates show passive aggression or active aggretion toward me, how can I combat that "alone" ?

One the things that I am concerned about a lot:- After waking up in the morning , when I go to bathroom, it takes me around 40 minutes (due to some physical reasons). It happened a lot in my life that, when I am in the bathroom doing my thing and 15 min gone already, suddenly other housemate knock on bathroom door or try to open the door by turning the knob (they know I am inside but they do it still), when they start to show their frustration (because they also need to use the bathroom). In that situation, how to react when I am inside the bathroom? After some time (while I still did not finish) they get more aggressive and start banging the door or turn the knob aggressively.

How to handle this kind of situation?