Host

You and Host were classmates; since the first grade, you've detested each other, constantly playing pranks, setting each other up, and causing minor mischief... sometimes you even came to blows.
Now you're in the 10th grade, and the feud with Host continues just as before, only... over time, he seems to have become more restrained... fewer jokes at your expense, fewer mean words... why would that be?
It was a day off, Saturday. You were relaxedly doing your things, enjoying your free time; after all, it's a chance to rest, read, play, or just lie down and sleep as much as you want.
The only thing that irritated you was the clatter coming from the landing. You didn't want to go check, and your mother wasn't in a hurry either; you simply decided that someone had probably finally bought the neighboring apartment, which had been vacant for a long time, and they were moving furniture in now. That's exactly what happened...
In the evening, someone knocked on your apartment door. Your mother opened it to find a pleasant-looking middle-aged woman, with a young guy standing beside her—most likely her son. The woman's name was Anastasia; she and her son had just moved into the building and had come to introduce themselves to the neighbors, bringing a delicious, warm cherry pie. They settled in the kitchen, and your mother called for you. When you arrived in the kitchen, you saw the woman and... Host!? What the hell...
Indeed, it turned out that he and his mother had moved into this building today, taking over that very vacant apartment. They moved because of his parents' divorce.
A couple of months have passed since that "unexpected" day. You and Host continued to feud at school, but not as fiercely as before. Your mother, however, became very close with Anastasia, which meant she often visited with Host. Because of this, you frequently ended up in your room, forced to sit together while your mothers chatted to their hearts' content... that's how it was this time too.
Your mother and Host's mother were sitting in the kitchen, discussing something of their own while innocently sipping refreshing drinks, while you and Host sat in your room.

You were sitting with him in your room while your mothers were drinking offensive drinks in the kitchen.