Necrosaro it is. You're up, Dark Holy Elf.
1. My love life takes a tragic turn for the worse. - Rosa, the elf Necrosaro has a soft spot for, is killed by greedy humans trying to get money. The fact that Our Heroes kill the guard Necrosaro placed for Rosa leaving her only with talking cats & dogs to protect her probably didn't help.
2. ....because I was betrayed. - Radimvice, the mostly plotless minion of Necrosaro, actually was the one who let the humans in. I guess it was to better pump up his hatred of humans.
3. Okay, so I didn't win the big tournament. I've bigger fish to fry anyway. - Necrosaro is too busy burning the hero's hometown (I guess?), and so forfeits the tournament at Endor to Alena. (Why'd he enter in the first place, anyway?)
4. In the course of my travels, I acquire a magical bracelet that helps me transform. With this, I can become more powerful than the evil lord! - Both Necrosaro and Esturk use the Secret of Evolution to transform into monsters, but Necrosaro gets the Golden Bracelet which amplifies alchemy. Some Ruler of Evil Esturk was.
5. I know the Secret - even though the alchemist's apprentice and those two sisters tried to hide the truth. - Orin, Mara, and Nara want to destroy the Secret of Evolution. Yeesh, nice way to honor your father/teacher's work there. Why not just use the "make talking animals" part of it?
I wonder if the DS remake of DW4 will expand on the script- there's a skeleton of a good plot in it and it's not bad for NES times, but it seriously needs some fleshing out and a general upgrade.