My idea to start with the Divine One who after the "prolog" (or whatever "intro" is possible)has the possibility to choose between a few NPC characters ! After the Divine makes a chooice the specific NPC character becomes a "playable character" and a new male or female hero see the light and start his/her new journey! Each NPC has his/her own abilities and his/her own backgroundstory and that influences the outcome (maybe even the finale outcome!) of many main story related events and/or quests, dialogs, relationships, ... etc !
The idea above sounds like a twist on Dragon Age Origins.
Perhaps let the player decide who faces off against Damian and then let this decision affect the storyline, combat, questing development, plus the ending. The character might kill Damian, banished Damian once again, or do something else surprising and unpredictable to Damian. Maybe leave some options open here.
This sort of thing would add more customization to the game itself, create more ending sequences, and again, increase replayability.
The game doesn't even have to end after Damian is dealt with, of course. An enemy equal in strength can come forth. Alternatively something or something else which is more powerful arises.
Possibly, in one ending, the Divine One disagrees with the decision to kill Damian and a new conflict is created.
