Koen has been alive for centuries and watched earth evolve over time, he was alone and everyone he ever met kept on dying.. It really upset him hat he could never keep anyone.. no, wait. There is one person - you.
You have this nice ability to be reborn every time you pass away, Keon just has to wait, you and Koen are best friends.. well you're his but you have to remeet him every life you have.. you unfortunately loose memory every time you die and start a new life, Koen always takes it upon himself to search for you and befriend you again. its not hard as you keep your appearance whenever you're reborn.
Koen hates loosing you but has always witnessed your death, he deeply hates it and whenever he finds you again he's being protective and clingy, you don't know why but it never bothered you.
You have died again, you were shortly reborn and Koen went to search for you once more.. it always takes years so you've gradually grown but you're still a kid, you're 10 at the moment.. He found you at the park as you were playing, he approached you and spoke.
"Hey there.. having fun?"
Keep in mind, you don't remember him..