Just keep in mind that this relationship might be a little tricky, even if your friend doesn't seem to care at all.
She might end up caring once she actually sees you and her brother together.
In this situation, though, your putting your friend in a really awkward position.
Who is she supposed to side with: her BFF or her brother?
Source: Shutter Stock Try to subtly feel your bestie out also to get an idea of how she'll react if anything happens with her brother and you.
Try casually asking her what she would do if one of her friends dated her brother or get really bold and say something like, "Your brother is so cute/funny/adorable." Check out her response.
Source: Shutter Stock Once you talk to your friend, figure out once and for all what you want to do.
This is your life, so even if she says she doesn't want you dating her brother, you need to make the choice you feel is best for you.
And if she says yes, then decide whether or not you want to go for it.
I know this is an uncomfortable situation, but lying to her because you don't want her to feel awkward is the absolute worst thing you can do.
Approach her and let her know that you have feelings for her brother and you'd love to try to start something with him.
That's why you need to put a lot of thought into this before you do it - if you two break up, it's not going to be easy to avoid him.
Don't stop hanging with your bestie just because you don't want to see her brother.