Those are both good ideas. The small view's black background makes the piece darker, but when in full view, the black background and the dark feel it gave to the piece is gone. So, if you add a black or just dark background around the purple area Kogomi's in as well as some darker shading and colours on her figure, it would look like something<mental, socially or physically> has made her break down and feel left on her own in the hazy confusion. Hell, you could alter it to just be black, grey and white as the colours and get a Noir-like feel.