He
When Elphaba first knew him, he was a shallow, spoiled Winkie prince. Glinda loved him, and she was fine with that. They deserved each other.
But when they rescued the Lion Cub…he began to change. He wasn't really as shallow as she thought at first. He could care about people, and love them…
And he broke up with Glinda.
He saved her, twice, from the Wizard. He saved her, and they took him away to be tortured or killed. She saved him, then. They travel together now. They don't know where they're going, and they don't care.
Because he loves her.
And because she loves him too…