Firstly, this is a lovely piece, with a really sweet air to it - the little kiss is gorgeous. The designs and overall conformation are wonderful, and their expressions are very cute.
There are a few little anatomy quirks; Mercy's neck, stretched as it is, is a little narrow where it hits the head, thus the left/near shoulder needs to be shifted forward and dropped a bit to fill her out. Her back is a little too straight, even though she's stretched.
With Lil' Ryu; possibly he needs a little dip between neck and withers to separate them. Otherwise it's fantastic.