Oh noes, a forrin woman...
I hope your brother knows the following if she is non EU:
If he plans to bring her in, he needs to have continuous 6 month employment history at certain wage and several thousand (3k ish) in the bank to stump up for application fee
and NHS fee. She has to stay out of UK while they apply, which can take many months. (True of all non EU spouses). A lot of paperwork needs to be tracked down and proving the relationship will most likely be an arseache for them.
If he plans to leave for while to live with her there and he loses his 6 months continuous employment, he will have to return to UK alone to work for 6 months again before they can apply while she stays at home. A separation of up to a year can happen... unless he has over 60k cash in bank (assets like house do not count).
She could be stuck alone, potentially with a baby on the way or arrived, before they can live together in the UK.
Even the most committed couples suffer ..
I married a British man and I adore him but so help me God I would not recommend this path to anyone. The UK rules are unconscionable and the separations they necessitate intolerable. And when you shell out £1000 for the NHS fee for the first 2.5 years, it's hard not to feel as if you are being robbed.