I relate so fking much here. There was someone who's not my biological brother, but i treat him like a brother and he treat me like a lil sis. One night he told me something like, "promise me you'll never forget me, even after you grew up and got married" he wasn't sick or anything but it seems like he knew his time was up, he died the very next morning on a car accident on the way to school.
That was 7 years ago, I'm 22 now and I'm still keeping my promise to never forget him 😭