Thanks a lot for your support, everyone! I'm really, really
touched, but because of time constraints, I can only focus on the
most pressing replies: 
From EllisBeck:
Now, this is the difficult part of it all - IGNORE her when
she's throwing a temper tantrum. Pretend nothing is happening.
But if we keep on ignoring her, wouldn't she get more and more
daring?
In fact, for the past 5 years, I haven't quarrel a single time with
her, although my mom and dad have, several times.
My ties with her is always neutral-good and that's because I never
say out how much I wanted to bash her like a sicko whenever she
abuses my bro and throws extreme temper.
From Yunhaier:
She is the middle child and usually middle child is subjected
problems (unless he/she is the only son or daughter in the family,
which could negate the effect).
How can this be? In theory, the middle child is the most
comfortable, because the 1st child has heavy responsibility(tough
life) while the youngest gets bullied the easiest(tough life). The
2nd child has the best of both worlds, in theory.
From LinLing:
A question: Do you mean that whenever someone visits, like your
grandparents/relatives/friends..., she behave very well?
Well, if it is yes, all the more you should ask them to visit.
Especially grandparents as children are usually meek in front of
them.
Yes, she's very nice to her friends and outsiders. Whenever we
visit our relatives' house etc., she's such an angel! :mad:
But my mom has told my aunts about her tempers and how she
verbal-abuse my bro, and they know about it too.
You and your family members excluding your sister MUST tell him
or advise him to be STRONG and CONFIDENT and don't be so scared. If
the sister yells at him, yell back. If the sister hits you, tell
them.
Yeah, after reading from one of the posts here about how this
kind of abuse can affect my brother's attitude towards women in
future, I feel even more anxious.
The best way would be for him to beat/scold her back; this way, my
parents and I have nothing to worry about anymore, because he can
take care of himself.
He's currently 13 years old now and his voice is only starting to
break. Boys complete their full puberty stage at late 14 - 15 years
old or so. Is it true that they'll turn more aggresive during this
stage?
What I'm worried is that my brother may have been so used and
immune to my sister's scoldings that he forever doesn't dare to
fight/say/scold back.
Worse still, he's the kind who always play those MapleStory online
games, not those ah-beng-potential types. Should my parents and me
keep encouraging my brother to stand up for himself and fight
back?
Because today when my brother isn't around, my mom adviced my
sister to change her temper and her attitude towards my bro. My mom
talked in a nice tone to her but the moment she heard it, she
turned rather fiery and very defensive, aggresive. My mom also told
her not to treat my bro this way, because he's no longer a kid and
is a teen now and may take revenge in future.
Actually, my sis isn't like this all the time, though. Most of the
time, she just ignores my brother. But when she's in a foul mood or
has totally nothing to do(like if she and my bro are alone at
home), then she starts to find fault and start those very fierce
verbal-abuse.
Actually, my bro is not 100% right either. For example, sometimes,
he leaves a couple of books on the sofa after reading, or leaves
some tissues around the floor, or forgets to lift the toilet seat
up when urinating etc......and for such cases, my sis gets very
very angry and starts those verbal-abuse again. But even though my
brother does these things sometimes, there's still no reason for
her to shout like that, right?
Thanks!
Nikar.
