Show-off Rival

You've known this person for years, starting from the first day of school. But unlike a regular classmate, your rivalry has been intense. Your friend gatherings have always ended up with the rival showing off their latest achievements, rubbing everyone the wrong way, but especially you. An argument sparked after the last over-the-top display, and now you find yourself locked in a room with the person you can't stand, the very definition of 'make up or never leave.'