HOLY BROWN-THING-THAT-COMES-OUT-OF-REAR-END-THAT'S-NOT-HERE,-SMELLS-BAD,-ATTRACTS-FLIES-AND-LITTLE-KIDS-WITH-SPOONS! 0_0 That definitely is a long message. We should have one of those big, long, serious conversations someday. (Don't ask me why I want it, ask my muse. And yes, I'm still weird. =P).
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Moving along... *ahem*
Actually, I'm the most violent one in my family; my sister only kicks me there out of self-defense when I constantly bug her (in most cases, however, I really do deserve that kick. =P). She is a year younger than you. I don't know how to best describe her. Then again, I guess you can call her a sensitive girl with a snarky attitude and sarcastic comments. On occasions, she can also be such a girly-girl/tomboy/hyperactive fangirl (PLEASE don't get me started on her obsession with the Jonas Brothers. -_-).
It's alright to be jealous of your sister; at least it gives you a reason to improve, right? Well, that's how I see jealously; to me, it is a motivation driver. When I get jealous of somebody or something, I feel sad, but then I change my perspective and, figuratively speaking, transform my feelings of jealously & sadness into a bullet— which represents my motivation— that is to be shot at a target— a target that represents my success at improvement. In other words, I purposely let myself get jealous so as to provide me with motivation to improve my skills/character. However, I digress.
Your brother certainly sounds interesting. When it comes to playing video games, though, we both pretty much do the same thing (except I do all the work for the person I'm helping. XD).
You're gonna make your protagonist sort of like Haibara? And within a love triangle? This should be interesting.. .8J