Adorable shot, that little girl's expression is especially lovely. A very sweet moment between the big brother and his little sister. :-) I think the Hello Kitty is a wee bit distracting (the block bit of white) so I'd have taken the headband off her before taking the shot. I would like to see this with slightly brighter highlights, midtones and some deepened contrast. Very nice shot overall.
Sweet capture -- these two so obviously love and enjoy one another. Wish the tones were as lively as the expressions -- maybe adjust the levels? And I would rotate clockwise just a little bit.