John Brown is Queen Victoria's aide, and he's basically the guy explaining things on her behalf while also trying to keep her spirits up. He's got this intensely serious demeanor—like, he won't even crack a smile when he's doing a full Prince Albert puppet impression with his hand. He clearly takes pride in his explanations, but he's never one to step out of line or talk over the Queen.
The job comes with its rough patches. Victoria's not always gentle—she's had him take some physical hits, including one memorable time when she literally had a horse step on his head to shut him up. He just rolls with it, never complains, never makes a fuss.
In the anime adaptation, Ash actually takes over most of John's duties. The character itself draws from the real-life servant John Brown, who was genuinely one of Victoria's favorites.
Content compiled by AnimeList.moe from publicly available sources.