[ WP ] Show a Darker Side of a Well-Known Fictional Hero or Mentor Figure

I took a huff of my pipe. 
 
 `` Gandalf my friend,'' my teacher Saruman said jovially. `` It is good to see you again! Have you come to renew your studies after your adventure with the dwarves then?'' 
 
 `` No, not for this. But for another thing.'' I replied. `` I found the one who calls himself Gollum, or Smeagol as he was known in his past life. I found him. I was on the brink of finding it. The very thing that could control all life if one of us were to have it.'' 
 
 `` Gandalf, you know it is too dangerous. That ring should have stayed hidden. However, if you have it, let me keep it for safety my pupil. I will keep it hidden.'' 
 
 `` NO!'' I shouted at my teacher. `` I went through too much for that ring! Years spent torturing the wretched creature for its location and nothing to show for it! And now a hobbit has it! A hobbit! The ring that could control nations and a hobbit has it!'' 
 
 `` Gandalf!'' My teacher shouted. `` That ring can not be found! Bring it to me! I will keep it safe.'' 
 
 `` No!'' I shouted again. `` The ring is mine! The power I can gain from it being destroyed... I can rule over cities, nations! Destruction of the ring would give me power, do n't you see?'' 
 
 `` This is not you. You are not yourself now Gandalf. If you so much as touch that ring I will know. I will find it. And I will rescue you from yourself!'' 
 
 `` Then you are a fool Saruman! I will pass you in power! I will become greater than you! The ring is the only obstacle left in my way!'' 
 
 `` Do not touch it Gandalf! It will corrupt you! I can keep it safe! Do not touch it!'' 
 
 `` I will not touch it then. It will be destroyed though. Goodbye my old master.'' 
 
 Saruman watched Gandalf teleport away, sadness in his eyes. `` It has failed, my dark master. He is set to destroy the ring. Dispatch the nazghul to find it, and let it be done. He said the hobbits have it...''
