over a year ago:
I definitely agree wtih norishima that he already does show Cristina appreciation. I mean in S5 when Mer wouldn't stop crying after she watched the execution he knew that she needed Cristina and went to her. He has always been more open to a relationship with her then she has been with him. I think in the beginning Derek was jealous of their relationship but lately it has seemed that Cristina has been more jealous of Mer/Der relationship.
And knowing Shondra they will not become just one big happy family.
But I do think that Derek will be eternally grateful to her.