She get's knocked out by Conan's dart SO MANY times.
Serena is also a childhood friend of Rachel Moore (Ran Mori) & Jimmy Kudo (Shinichi Kudou)  , and also the second daughter of Samuel Sebastian  (鈴木 史郎 Suzuki Shirō in Japanese), the owner of Sebastian Financial Group (Suzuki Financial Group in Japanese verson)  (鈴木財閥 Suzuki Zaibatsu in Japanese). She is flighty and perky, and yet is also a very loyal friend for Rachel, as well as quite less spoiled than it's expected from her social background.
Taken from Wikipedia:
She has a love for flirting with cute boys. Serena has a typical additude that would come from a girl her age. She often teases Rachel for the fact that she knows that Rachel still loves Jimmy Kudo (Shin'ichi Kudo) . Although she is still in a "seeking" mode, her actual, constant boyfriend is Makoto Kyogoku who she does love very much. In fact, she's often sad over how she doesn't see Makoto often, and later worried when he didn't call her for a few days, thinking that he didn't love her anymore. She even sent him a vase she made, and made chocolate for him at a mountain lodge famous for having its chocolate keep lovers together (she tried to make him a sweater as well, but it turned out to be too hard and she quit half way through).