I have a feeling it's titled this way because "Ozy and Millie" flows better than "Millie and Ozy"Yet, the strip is called "Ozy and Millie", not "Millie and Ozy"...In spite of what I said earlier, I see Ozy as the secondary character. Millie is the one who gets up to all these crazy antics, and Ozy follows her around and joins in. It's very rare to see Ozy come up with an adventure; he is more of the voice of reason and the means of execution.
but iono, that's my thought.