I'd love to have someone to whisper pet names to
That being said it would probably be something fitted to who they are, maybe a favorite food, or related to something interesting, in addition to sweetie, baby, honey, cupcake. Something we both found adorable that was related to her. Maybe if they were feisty I could call them my little firecracker

hahaha.
I've had some interesting pet names thrown my way though by women I was good friends with. The weirdest one I think I got was child.