Like Mrs. Olinski, Mr. Singh has secret pain in his past. He's been widowed too. And they've both settled down—Mrs. Olinski to a wheelchair, and Mr. Singh to a house in upstate New York. Yeah, that might seem pretty different. But if you've been cruising around the world, buying a house might seem a lot like giving up your legs.
So, why does Mr. Sing do it? Julian. It was time, Julian says, for them to "settle down" ("Ethan".30).
Running a bed-and-breakfast is a natural second career for Mr. Singh. He's a good cook, sure, but his primary characteristic seems to be the ability to make people feel better—and to sum up moral lessons in wise, cryptic-sounding sentences. Like this: "How can you know what is missing if you've never met it? You must know of something's existence before you can notice its absence. So it was with The Souls. They found on their journeys what you found at Sillington House" (11.27).
Presumably, Mr. Singh has been on some sort of journey, too. By the time we meet him, though, he's been there and back again and gained the kind of weird, spooky wisdom that helps him know right when Mrs. Olinski is reaching her breaking point, and exactly what kind of journey Ethan has been on.
Mr. Singh isn't exactly a character in his own right. He's not well-rounded and he's not particularly believable. But he matters to the book. A lot of parents would have been all up in Julian's business, and maybe not been too thrilled about hosting a bunch of 11-year-olds in their place of business every Saturday. But Mr. Singh is. He gives them room to discover themselves, and he gives them the physical room to do it in.