This is for the backstory of the Kagamine Twins in The Jekyll and Hyde Love Triangle. I want to spoil it, but then again, I don't want to. All I will say is that something happened to Rin and Len's parents, and Len was a bit mad, and it's the reason why he's evil. Even so, Len sometimes wishes he didn't leave his sister, when he realised he needed his older sister. And in this picture, it shows how Rin and Len miss each other. The light and dark shining shows which Kagamine is good, and which Kagamine is evil. I'm pretty sure you can tell who is what.

Len: Why did I leave her?
Rin: Len, why did you have to go and leave me behind?
Len: Rin...my older sister...I'm sorry...I'm so sorry...
Rin: Oh Len...if only you knew how much I miss you, little bro...
Rin/Len: I love you...so much...I wish I was here with you...to make you happy, and to protect you...