Catherine is a quite attractive half-Japanese/half-Caucasian girl who dresses in a normal fashion for a girl of the age of 18. She wears her hair long but has an odd tendency to look decidedly Goth after casting spells as the magic has a sympathetic resonance with her, which is odd given she's surprisingly upbeat.
In a world of absolute weirdos, Catherine is totally level headed. That makes her a kind of insane. The only time she ever displays any serious oddities is when exposed to new science or magic, in which she develops a mad scientist like obsession that does her grandfather proud. She blames this on imbalances in the humours, honest.
Otherwise, she's the straight woman for much of what goes on at Claremont.
Catherine Drake is the younger half-sister of Lucien Drake, though their bloodline is through their shared demonic parent rather than through their mother. Despite this, Catherine is treated as a second daughter to Doctor Danger who educates her in all manner of odd laboratory work in-between her own study of sorcery under the enigmatic Eldrich. Catherine was briefly a member of the Gemstone Girls but has since gotten her demonic side under control. Dauntless has a crush on her, as does a substantial amount of the male student body. Catherine, on the other hand, is mostly just interested in finishing her studies at this point.
Catherine is a sorceress, much like a number of the people involved in the game but her knowledge is primarily devoted towards dismissing and summoning spirits. As she said "I have the Summoner Class, Not Black Mage or White mage like the Cherry Twins." She also has demonic regeneration and can assume a demonic form when exposed to extensive amounts of black magic. Because she's half-succubus, she can also enchant anyone she meets of the appropriate sexual persuasion. Bizarrely, she's a bit of a prude.
Catherine is "Seven" in this game and merges Lucien's concept with his sister, who was part of the Gemstone girls.