I want to preface this by saying I do not identify as a brat, and so if you are trying to find out these answers from the perspective of someone who does, my response probably won't be very helpful 
If I'm being bratty it's either because I am cranky (tired, hungry, whatever) or because my Daddy is not providing the appropriate structure in our relationship (which doesn't happen very often anymore but came up a lot when we first started dating).
Now that my Daddy has had lots of practice, He is excellent at handling my bratty behavior. He always starts by correcting me, then follows up by asking if something is wrong/if I ate breakfast/how I slept last night/etc. We talk about it, and then if He feels a punishment is warranted He gives me one (or if it is something that requires privacy, we may schedule it for a later time).