You didn't know why, but your Dad loved blocking doors since you were young. It was a game. He'd put himself in front of openings to try to keep you from getting past, but he was too slender and you were always too small and fast, managing to get through every time. You weren't sure why he did this, but you got the sense that it bothered him when you realized he had started putting on weight.
It wasn't long before he was taking up more space in the doorways, his waist wider in the frame. He had grown slower, easier to escape his grasp, but the fit was tighter. Still you couldn't help but watch him slowly grow, filling out every space he fit in with his ever increasing mass. It wasn't long until he'd grown out of his housewear, forced to go around in just briefs that barely fit him anymore.
You didn't even try going through the doors he blocked anymore. He'd grown so large you couldn't even squeeze past hallways with him in them, forcing you to find a way around. He continued growing fatter and fatter, his big belly on constant display hanging out in front of him, filling every space he was in. His chest was almost just as wide now, two fat tits sitting under his shoulders. He continued growing even after you moved out, his face filling out more and more on your calls.
It wasn't until you headed home for a visit did you realize what this game meant to him- You weren't allowed inside until you gave him a hug. You were quickly smothered by his warm cuddly embrace that warmed you to the core. He seemed to glow happier than he'd ever been, moving out of the way to let you in. Now you made sure to hug him every chance you got, reminded of the safety and protection he gave you. You knew he'd rubbed off on you, and that one day you'd grow to his size to show your love.