See? Told you it wouldn't take long! But sorry it's so short...
The Tin Man was more furious than anything. He sprinted through the halls of the grand castle, following the soft footsteps of the witch as she tried to escape from his rage. Had he possessed a heart, it would have been pounding and ready to burst.
She's dead and it's your fault! It's ALL your fault!
Emotions surged like electricity through his metal body: anger, the most prominent; grief, heart- (or lack thereof) wrenching grief; and, at the back of his mind, sadness, sadness for the girl he may have loved, that he never got the courage to ask her if she loved him as well. All these feelings fueled his fury, shoving him on toward the green woman that stole his happiness away from him. But he suddenly noticed that it was more silent than a moment ago.
He paused for a moment, listening; the footsteps had ceased. He had lost all heading.
Dammit…
Anger built to a painful climax again, just as it had below the balcony when he had screamed for the witch to show herself. No bothering to harness or suppress it, he pounded the nearest wall in a frenzy. Though the brick held, unaffected, his thin metal knuckles finally split. He ignored the pain and kept pounding, as though he could shatter the wall and see Dorothy standing there with her soft, pale skin and her gentle brown eyes…
He cried out in grief and slipped hopelessly to his knees, sobbing, not caring if he rusted, but rather wishing he would. He wished he could just rust and stay there for eternity. Maybe the witch would be merciful and kill him, too. She had her slippers now, there was nothing stopping her from destroying Oz.
Amidst his despair, he hardly heard the witch's cackle echoing through the castle:
"That little farm girl's stiff as wood!
Mourn your loss, she's gone for good!
Come and find me, rip me apart,
Because I know you have no heart!"
The Tin Man tensed at the witch's taunting song. She wanted him to kill her? Why? Sorrow and resentment clouded his mind, and he didn't care about the whys anymore. Slowly, fueled once more by hatred, he rose to his feet. His face was the picture of revenge, and his split knuckles made him all the more terrifying. Had Dorothy seen him, she would have been horrified: his innocent, timid persona had melted away, revealing a man who would fight for and avenge what he cared for most.
With new reason, and a refreshed loathing for the witch, he turned and followed the voice up higher and higher into the foreboding castle.