My brother asked me, we are orphans, he didn't really know my fiancé, and said he just kind of thought someone should ask? I've now been married 12 years and fiancé and brother get on fine.
My husband wishes he'd asked his brother if he was sure. First time his brother got married, she left him with a bunch of debts after 2 years, moved country, and was never really heard from again. And his brother isn't that bad.