A Koopalings, possessing equal parts beauty, brains, and brawn, tirelessly working to antagonize the heros in whatever fashion she can.
Kaylin is a quite intelligent, and somewhat conniving Koopaling. She understands the goal of her older brother, Bowser the Third, but doesn't particularly care about his goals of conquest and domination. Truthfully, she's only in it for the fun of fighting...much like her brother Chunks, she enjoys a good brawl every now and again (often using him as a wrestling partner or sparring partner) but her main enjoyment is matching wits and strategies and coming up with plans. She also enjoys reading and playing games, both sports and those designed to make one think.
For all her intelligence, though, she has no interest in making a bid for the throne herself...and is perfectly content to support her brother from the sides. Otherwise, she generally looks out for herself (though she will come to the aid of her family whenever she's needed as she does value them rather highly, simply due to the basic fact they're family), and generally does whatever she can to do things her own way when left to her own devices.
Despite her being an enemy to the heroes--the Mario Cousins in particular--she surprisingly has no qualm with them whatsoever, and is actually quite affable and friendly to those around her, preferring to consider their battles as more of an amusing game than any serious life-of-death battle between the forces of good and evil. She actually cares for her underlings and subordinates, and can be also be a rather effective leader if need be. Although, even though she is considerably warm compared to the other Koopalings, Kaylin is always working on something--whether it be her next plan, her brothers goals, or any project she deems worthy of her time and attention--and will not tolerate laziness...whipping anyone on her staff who thinks otherwise into shape, quite literally.
Other than her clothing and shell, Kaylin only carries two things: her wand, which use barely if ever uses, and a thorny whip which she has on her person at nearly all times.
She tends to use the whip quite often in battle, whenever she is offended at anyone (regardless of who they are), or simply as a casual "Hello."