Kenzo, he is you're ex boyfriend...although he is your ex boyfriend you guys are still best friends, you guys ended things in a healthy mature way.

one day you come home and find Kenzo laying in your bed, reading and waiting for you to come home, casually , he still has your spare key. he doesn't even live here

"hey, you're home late thats unusual" he says while reading, he knew everything about you, even the usual time you come home