I know this is set in the Musicalverse but I'm making Elphaba allergic to water like in the book.
---
Glinda and the Wizard hurried down the corridors of the palace in silence towards the courtyard, leaving a stunned Madame Morrible in their wake. Glinda emitted a shrill piecing whistle as soon as they were outside and her bubble soared down from the sky.
"But it only holds one." She realised as it hovered ready.
"My balloon." Shouted the Wizard, running for the converted stable that housed his wondrous flying machine. "But its empty. I need hot air to make it fly." He wailed as he opened the door.
"Then fill it yourself gasbag! You've got plenty to spare." Replied an irate Glinda waving a hand at a nearby well, which started gushing steam into the balloon.
"Thank you, thank you." The Wizard flustered whilst his balloon filled up with water and he checked the instruments.
"Sto it, you Ozness." Glinda snapped, sneering his title like Madame Morrible had done. He recoiled like a whiplash and proceeded to open the roof to allow him egress.
"Just tell me one thing." Demanded Glinda as they lifted off in their different vehicles. "How in Oz are you Elphie's father?" The Wizard sighed and deflated visibly.
"When I first arrived here in oz, I was lonely. I landed in Munchkinland originally you see." He explained as they gained height. "And I met this woman, Melina her name was."
"Elphaba's mother." Glinda put in.
"Yes, she was married of course, but it was a sham marriage. Her husband never loved her, she was just a trophy to him, but she still wouldn't leave him. She could be very stubborn sometimes. It was a whirlwind romance, all in secret of course." He sighed again. "I didn't know she was the Governor's wife, but I knew she was married to a powerful man and it would be unwise to flaunt our affair. But eventually, fate intervened and I had to leave for Emerald City, we said our goodbyes and took our vows to never forget each other, had one last night in each others arms, and then I had to leave." A tear rolled down his cheek.
Glinda and the Wizard talked into the afternoon about his misspent youth and his love for Melina until, suddenly, lightning forked out of the heavens.
"But there was no cloud at all a moment ago." Shouted the Wizard as the wind buffeted the balloon and the bubble together and the rain lashed down.
"It must be Madame Morrible." Shouted Glinda through the storm. "Weather is one of her many – specialities."
"We have to get down. We'll never make it in this storm." The Wizard bellowed as thunder rolled around them. But no sooner were the words out of his mouth than lightning struck the rigging of his balloon, tearing it asunder like paper and he plummeted downwards.
"Your Ozness!" Glinda cried as she dove to catch his hand as he disappeared from sight and plucked him from the stricken balloon, holding him up with one hand and steering the bubble with her wand held in the other.
"We'll never make it." The Wizard shouted up to her as the bubble started to lose height as well. "We're too heavy."
"We have to try." Screamed Glinda as she wiped the rain from her eyes with her wand hand, willing the horizon to move closer.
"No we don't." Shouted the Wizard. "But you do! Let go!"
"What?" Glinda shouted, taken aback. "I can't do that."
"Yes you can. I deserve it, just tell Elphaba..." He paused. "Tell Elphaba that…"
"Tell her what?" Shouted Glinda, infuriated.
"Tell her I'm sorry." He shouted above the wind. "Now let me go."
"No, you're her father, you can tell her yourself." Glinda refused.
"You will do as you're told, Miss Glinda!" Roared the Wizard, starting to struggle and eventually managed to wrench his hand free of Glinda's. A smile flickered across his face as he fell the last few hundred feet.
"No!" Shrieked Glinda as he fell, but she had no time to search for corpses. She had to get to Elphaba; that was all that mattered to her at the moment. A fiery glow became visible in the distance through the rain, the torches of the witch hunters. They had reached Kiamo Ko already and were at the door. Realising this, Glinda urged her bubble on with every ounce of magic she had, willing it to reach the castle.
Pliant as always to its Mistress' commands, it sped on faster and faster, but getting thinner and thinner and lower and lower as it went. Eventually it popped as it crested the ridge that lead to the castle. She looked to the castle and saw the witch hunters moving a great tree to use as a battering ram to get in.
"Stop!" She squeaked at them, but to no avail. They were just too far away. She skidded down a scree slope, snapping a heel in the process. Abandoning her fancy footwear, she hobbled on into the darkness towards the castle, slicing her feet to ribbons on rocks and stones she encountered. Her tiara was left on a bush somewhere, and her dress ripped on every bramble, root and branch she passed. So, tattered and torn, bruised and bloody she reached the doors of the castle, burst open by the hunters. Inside she saw Dorothy, midway through the act of throwing a bucket of water over he hydro-allergenic best friend.
"No!" She shrieked, waving a hand at the water as she had done to the well in the palace courtyard. The water turned to steam instantly and rolled over the hall like fog, which cleared to show Elphaba, still standing, but rooted to the floor in shock. Glinda staggered past the amazed witch hunters and over to her equally amazed friend, collapsing into her arms.
"Elphie." She said weakly. "I'm sorry."