Caius deeply enjoys his time with the mild-mannered Cherub. She's softspoken, charming, and an absolutely wonderful listener. While she may be interested in literatures quite different from Caius's own tastes, she's still always eager to hear of Caius's latest readings and findings. Caius will humor Cherub and offer to borrow her latest pieces of fiction, under the guise of "proofreading"... when, in secret reality, Caius finds the provocative writings to be quite an entertaining (and absolutely tantalizing!) read.

Despite being an unreliable idiot (Caius's words), Somnus unfortunately works at the library Caius tends to frequent. When the Symprite is actually awake on the job, he can be quite useful in finding books and literature for Caius's studies - though he tries quite often to recommend books as well (typically fantasy or romance novels), Caius has yet to fall for Somnus's self-proclaimed "charm".

Though both are often busy with their own lives, the two siblings are supportive of one another's endeavors. While Caius finds Lucius to be an airhead most times, he finds his baby brother's starry-eyed personality endearing (though Caius would never admit such a thing).