Thank you! Yes, while JKR doesn't always develop her characters in depth, they almost always have the potential for depths, and just enough hints to make them interesting. Snape and Petunia make interesting parallels -- both obsessed with Lily, both abusive authority figures in Harry's life, both bitter and unpleasant in personality, both trying (in a backhanded, often ineffective way) to protect Harry. And yet we see such a lot of Snape, and so little of Petunia. So I liked writing Snape from Petunia's POV, because she is dismissive of him in a way I rarely see in fandom; it's fun to play with tropes and expectations like that.