We're not doing anything until I find my sister,' I say

You want to be an alchemist so badly? Don't wait to react to the immediate problem.
Plan ahead. Look at the big picture and you won't ever have to deal with that problem.
Better to save yourself from a major catastrophe than drag your feet over a bunch of little inconveniences.

There are certain things we owe our little sisters.

You mess with my sister, you're messing with me!

[S]isters could do a great deal for their brothers, if they would.

For a moment we glared at each other, stubborn as cats on the stable wall, full of mutual resentment and something darker, the old sense between sisters that there is only really room in the world for one girl. The sense that every fight could be to the death.