Beginnings
The beginning of their friendship really started with the hat. Once Elphaba got the peaked black hat, she began to warm up to Galinda. She felt horrible when she walked out onto the dance floor, and everything stopped…
But Galinda danced with her when everyone was too stunned to laugh at her. She had tricked Elphaba, and now she was apologizing. The woman who became Glinda danced with the future Witch…and no one remembers.
Elphaba accepted her apology, and that is how Glinda the Good and the Wicked Witch of the West became friends…over a hat.
The witch's hat was their friendship, in a way.