Robert_evrae explains that, as an immigrant, you wouldn't travel to a new country and openly admit to them that you're a thief or a murderer, would you? The option to become evil is and has always been available to you, just don't go around telling the proud folk of Imperial City you plan on worshipping Daedra within the first week of your arrival. You'll notice a lack of evil character options, but its exclusion makes sense. Characters include a wealthy merchant, a priest, or even a skilled craftsman. You're now able to choose from a range of character options most comparable to classic RPGs. No longer will you find yourself acting as a substitute exterminator for Uriel Septim. Fret not! The Alternate Start Arrive By Ship mod from Robert_evrae cuts out the rather laborious chore of an intro in favor of captaining a ship that just so happens to enter the port of either the Imperial City or Anvil. Help re-order mods, has a mod installer (BAIN), save-game manager, etc.

If youre ok with mods theres a set essential spell on tesnexus.

Alternately, you could use the console to ramp up the NPCs stats (like set their health to 1000 or something). Wrye Bash : necessary tool if you want to use mods. Of course, if the quest doesnt end upon the NPCs death, then you can just use the console to resurrect them. Oblivion's intro through the Imperial City's rat-infested prison catacombs can be a bit of a slog to get through, especially after repeated playthroughs. Essential Tools: not mods, but 3rd party tools to help keep a modded Oblivion running smoothly.

Essential mods for oblivion