This is my entry for "The World Ends With You" contest. This is actually two entries combined. The second is a background submission ([link]
Anyway the above characters are fraternal twins: Onei the younger twin (left) and Olwen the older(right). Although Olwen is the older sibling, she's very dependent on those close to her. Onei tends to be protective of his older sister, especially since Olwen clings to him a lot. Sometimes he has to get physical, hence his bandage on his right hand. Although they are twins, one could say Onei was born with the better genes.
If a back story is needed, I suppose I could say that both characters suddenly became involved with "The Reapers'" little game, Olwen more directly. She was the one who received a text message with their ultimatum. Onei received no such message and yet was pulled into the "game" due to his relationship with her. He has no need to play and faces no penalty of erasure, but his sister does. So he fending-off the Noise as he escorts his twin sister through her trials against "The Reapers."