Besides being the little sister, she has her own story. Charlotte is a first-year, yet she's already the captain of the swimming team, and she's a shoo-in for the honor roll. Her voice should be bold and fitting as the literal epitome of what a woman should be. Don't be afraid to use your real voice. I'm not looking for a super-high cutsie loli. You're athletic and independent, but don't confuse that with manly. You're not a tsundere.