I can't wait to see Heath/Darcy scenes. I think it will be an adorable relationship. Plus, I think Darcy is the one thing that might just manage to get Heath on the straight and narrow (eventually), and make him a more likeable character.
I agree with you completely, I have a feeling that their relationship is going to be really special, you could imagine the pair of them lighting up around each other, I just hope this is something we get to see from them. I don't particularly think that Heath is going to be 100% good but I truly believe that him getting to know his daughter is going to give him a totally new perspective on life, especially as spending just two minutes with such a cutie is enough to make anyone want to be better. She's perfect!