I think the same holds true in writing. If we introduce our protagonist at the same time as our secondary hero or villain or even at the same time as our heroine and bring them along together, they get too wrapped up in each other and co-dependent. They need to be introduced in separate events and each given time apart from the other to grow and show their strengths and weaknesses. In most romances I've read, the heroine enters on-stage first and we develop a relationship with her so that we see the hero through her eyes when he makes his entrance. But I think it's more than just POV. There is a lot to be said for giving our characters distance. They all thrive when they're grabbing attention.
Now if we can only decide which one of the dogs is the hero and which one is the anti-hero. They don't seem to want to follow script.