Nice shot, and it does have the ahh factor about it, although it looks as though Lucy has just lost focus (shallow DOF?)
We have twins (identical boys), and although twins are darned hard work when they are little, as toddlers they are good playmates for each other. During their teens, my two just wanted each other dead, and now in their late twenties, they remain best mates, but still have the odd 'disagreement'.
Twins do develop a much closer bond than ordinary siblings, even non identical twins, and as they get older they will hopefully use that special bond to help and support each other.