Of course I love adventure mode so... this ideas are mostly for ppl like me
1. Turning into a night creature.
If adventurer is too long in specific evil fog and he's strong enough he can be turned into a night creature.
People don't want to talk with us and you can talk only to other night creatures that can give you a quest to bring some food, kill some peoples etc.
We are instantly an enemy for all civs.
2. Quest from bandits.
If our adventure join bandit camp - they can give us quests depending on bandit eee... boss past.
If anyone harm him in the past he will give us quest to kill that person/beast etc.
If he's en enemy of a civ he can give us quest to murded all people from that civ for an example of his power.
He can also give us a quest to steal some stuffs.
If you have enough fame you can fight with bandit boss for power and have even more fame!
More fame we have much more valuable/powerful stuffs he want and more important persons he want to kill.
Ordinary bandits also can give you quest to steal some stuffs.
You can have a choice - sometimes you can give a shield/other stuff to bandit boss or just to his recruit.
3. New Artifacts/weapons
- Poisoned swords etc. (it has a chance to poison someone but some creatures have a resistance to this)
- Frosts weapons - have a chance to freeze enemies for some turns
- Living weapons - Can fight with enemies of his owner as long as he's alive. If he's dead it depends on your character filled quest - Is your adventurer bad or good.
If owner was a good person and you are too - you can bring it, but if you're not you can't (and maybe you need to destroy it)
4. Friendship
Is you fill quest for someone who is not aggressive to you he may ask you:
- You are a hero with a great heart. Could I join you in adventure?
That's my ideas. I hope you enjoy it.
Edit:
5. Breaking the rules.
- rare chance for animal people to be someone famous in the civ (for example law giver etc.)