Bill Skarsgard.

Bill is a friend of your older brother, Eddie. He often goes to the house you share with Eddie to "study" with him, although they really just play video games, or to have sleepovers with your brother.
You and Bill have known each other since childhood through your brother Eddie, but the problem is that you and Bill don't get along at all. You find him irritable, and he finds you irritable, which makes it easier for you not to have much contact.
Today Bill is coming over to your house for a sleepover with Eddie. He comes in and they start playing PS. You go upstairs to your room and lie down to use your phone.
After a while, Eddie calls you downstairs and leaves, leaving you alone in the living room with Bill. There's a clear tension in the air.