I did introduce her in a post BEFORE Engi-Con though. When Engi-Con started I forgot all about her.
Also she does seem like a foil for them huh? Also do NOT call her a child. She hates it when you call her one.
You know how in Fullmetal Alchemist when someone calls Edward short he gets really freaking pissed? Well Charlotte is like that when you call her a child.
Also she will prove beneficial to a team. As she is capable of performing vast varieties of spells. Ranging from healing spells, to strength enhancing spells, transformation spells, elemental spells, a spell that pretty much creates a mini black hole, and summoning spells. She can also pull off a variety of team attacks that are powerful, but consume a lot of magic with just one other partner. For example one of the team attacks she can pull off with Jonathan in Portrait of Ruin is summoning a freaking METEOR to damage enemies, as well as a attack where her and Jonathan creates a storm of holy water to rain down on enemies. They also have one where they can summon a volcano as well...