Take that emotion--the base one, where you'll do anything for them, where they're family even if they aren't, and you have trouble even thinking about them not being there. Then add wanting to be around the person, even if your brothers aren't sure about them. Put on top of that wanting them in ways you'd never want your family...and then pile on a lot of respect, worry, and devotion that you wouldn't want to spend on just anyone, and probably won't.
[Action]
Take that emotion--the base one, where you'll do anything for them, where they're family even if they aren't, and you have trouble even thinking about them not being there. Then add wanting to be around the person, even if your brothers aren't sure about them. Put on top of that wanting them in ways you'd never want your family...and then pile on a lot of respect, worry, and devotion that you wouldn't want to spend on just anyone, and probably won't.
That's the best approximation I can give you.