When did the Darkling lose his love of colors and stuff? Or is he still that same young boy inside? Is all the black just a dramatic statement or does he really not appreciate colors the same way anymore? BTW I looooooooove your books with burning passion

Thank you! 

The Darkling never lost his love of color. As Nikolai says (more or less), the Darkling understands the power of public image. Wearing black, keeping that color associated with his title and no one else is part of a carefully cultivated persona.