regulus is so used to hiding objects and stuff from his mother that even after leaving and now living somewhere else, he ALWAYS without fail, puts most of his stuff under something after using it (or at least hidden).
He's using his laptop in bed and he wants to tuck in for the night? he's putting his laptop under the bed/nightstand. Got a present from his brother? It's currently hidden in his sock drawer. He finished reading for the day? peter's going to find that book under the couch cushions next week.
And slowly, peter started doing the same without even realising it. After reading his favourite comic he's just push it under his pillow, his headphones is behind a stack of plates in the kitchen, and his passport is INSIDE one of his socks.
one time, they invited their friends over and they decided to play hide and seek. sirius thought it would be hilarious to hide in their room because regulus was the seeker, so he decided to hide under the bed and was so fucking confused why a screwdriver, several books, a box of washi tap, and three hoodies where under there like what???