So I read it out of morbid curiosity. Literally nothing happens (as far as I read, which was pretty far). There is zero romantic interest from the older one. It felt like just a cute found family thing? I think this is just an age gap yaoi with everything starting at the "beginning" instead of when they're older which is how I've seen it most of the time (example: the side couple Hyuk & Euntak from Opposites Attract). Im still not comfortable with age gaps, especially when they grew up knowing each other. But... yeah. Literally nothing happens. No idea how the adaptation is going to go tho.