The world was enormous, Alfred had believed once.
He'd never seen it, of course, but he knew because Arthur knew; and Arthur would tell him about it before bed time. As he snuggled against Arthur's massive chest, he heard stories of exotic-sounding places like Europe and Asia and Africa. He tasted them in teas and spices, he smelled them on Arthur's coat when he'd hug and kiss him upon their reunion.
Arthur was a hero, and before Alfred fell asleep he heard grand stories about this massive thing Arthur called 'the world'; and, especially, called his. Alfred would hug the thin, powerful arms in anticipation as he was let in on the gossip of monsters, savages, fairies, and unicorns. He'd gasp at the drama when Arthur would regale him with tales of how all of them were conquered, and giggle when they questioned British superiority.
Under the safety of calloused hands that stroked his hair, the world was mystical; and his brother was mystical for knowing it all.
Everything was Arthur's, and Arthur was everything. Alfred was Arthur's everything on the rare occasions he could make it back.
That made Alfred special; that made him mystical and huge, too. He thought it only fitting to think of his brother as he built and grew, and as he peeked into rooms in his home that he wasn't able to fully explore yet. Arthur wouldn't be scared of natives, beasts, Frenchmen, and Spaniards that blocked his path to destiny. He wouldn't pause, he'd just laugh in their faces and make them into a new trade route.
The world was just too small for Arthur, and it knew that it was because it lined up to fill his pockets. Alfred grew into these dreams of heroism as he grew into his new body.
He didn't know why he thought the world would grow with him, or why he thought Arthur would grow with him. Maybe he just wanted things larger than life to always be that way, no matter what the circumstances. Arthur should have towered over his slowly-refining homes, had arms that could still envelope him, and lived up to stories that couldn't possibly be true.
But the world didn't grow for anybody, he found.
Alfred stood over Arthur, and watched him sob in the mud over a colony he no longer had a right to. Maybe over inevitability, or something. Alfred stood and watched his brother shrink, and watched the world shrink along with him.
The world became manageable, mundane, and tiny from then on. Alfred couldn't really blame it; he just found heroes elsewhere.