Size.
They say size doesn't matter but Elphaba Thropp could attest to the fact that it did. Not the size everyone is always talking about, but another size.
The green woman found herself partial to petite figures, rather than masculine ones. She would choose someone much shorter and tinier than her any day over someone taller and bulkier.
Elphaba had never felt comfortable being held and coddled. She was always the one who wanted to do the holding and coddling.
This was a set back that she experienced throughout life until she met Glinda.
Glinda had been the perfect size for Elphaba. Not too short and yet not too tall, and the blonde wasn't more muscular than the green woman.
She was the perfect size for Elphaba to wrap her arms around and hold against her chest. Glinda's head would only reach up to her breasts, but Elphaba wouldn't have it any other way.
She loved the feel of Glinda so close to her. She felt fragile in her green arms, as if she would break from too tight of a hug.
Elphaba had never been allowed to play with toys as a child. Her only comfort was a piece of glass blown for her by Turtle Heart. Maybe that's why she preferred delicate and dainty over anything else. She had been taught to appreciate fragile things.
As Elphaba hugged Glinda she reminded herself of how well they fit together. Glinda fit perfectly in her arms.
She was the perfect size for Elphaba.