Rook says that he eventually transferred from Savanaclaw into Pomefiore because he wished to gain a deeper understanding of beauty, but also because of his desire to watch Vil hone his own beauty up close: “After all, two swordsmiths hammering a blade can give it an even keener edge. I volunteered to swing the second hammer upon Vil’s blade of beauty.”
Vil says that he actually tried to dissuade Rook from transferring, but before he knew it Rook was a Pomefiore dorm member. During his second birthday interview Vil tells Trey, “I’ve never understood why some people insist on changing their dorm after the Dark Mirror selected one for them…”
Rook will defend others from Vil’s ire, as seen during opening ceremonies (after Vil refers to the new students as half-priced potatoes).
It is Rook who encourages Vil to accept Ace and Deuce into the VDC team despite their faults, saying, “Imagine, if you will, a tiara packed with previous tones all crowding one another out. But another option is a tiara in which a single, grand diamond has a smaller, more colorful array of gems inlaid around it. Personally, I would find the latter more tasteful and appealing.”
Rook often advises Vil during Book 5, encouraging him to show Epel “the power of (Vil’s) beauty” after Epel runs out of a dance rehearsal in frustration, effectively saving their relationship. Rook also asks Vil to forgive Epel for his rudeness after Epel returns to the school.
While Vil is originally against the NRC team watching Neige’s performance Rook convinces him to allow it, indirectly leading to Vil’s overblot. (All three light-magic users—Kalim, Rook and Silver—were each overblot catalysts.)
Twisted Wonderland Reference Note 