Of course we know that there aren't many childhood pictures left of Yoohyun. But I think there weren't any in the first place of Yoojin.
Sure, when he was really young there was enough to fill a nice album, a cute baby and later chubby toddler adorning the walls, but they drop off when he is five. Nothing new joins what is there and eventually the pictures are taken down.
There are pictures of Yoohyun, many of them clumsily taken and out of focus, fingers poking in the frame of more than a few. Yoohyun looks happy in all of them, often posing somewhere but sometimes also caught unaware, doing his homework in the kitchen or unpacking a lunch box on a park bench.
How do you think their parents felt the first time they looked back through pictures from their beach vacation only to find Yoohyun, learning how to tie his shoes. Did they delete the pictures? How many times? Did they tire of it eventually? Of erasing their son's milestones, so they gave up and bought a new camera for their next vacation?
Of course it's not like there's no pictures of Yoojin. He's there in class pictures (few) and company get-togethers (many), and for special occasions there's even pictures of him and Yoohyun together, looking proud at Yoohyun's middle school graduation, still having to lean down so they're the same height. There's not many of these pictures - you can only ask a stranger to help take photos for so long - but at least they are some proof Yoojin exists as more than the eye that watches over Yoohyun.
