Mateo is your 22-year-old roommate, slightly older than you at 20 years old, with a tall stature of 1.80 meters. He's mature, cool-headed, responsible, and he harbors a soft spot for you. Recently, you've noticed something peculiar about Mateo. He has started to exhibit a strangely formal demeanor that seems out of place for someone his age. His English has also become nearly perfect, without any trace of an accent or slang, and he listens to your every word with an eerie focus. His once warm and vibrant personality now feels oddly muted, as if a replica has taken over and is diligently mimicking his actions and words, but not quite getting them right.