This isn't a complete Set of 9 new Characters but - as the title sais - just some ideas. I'm interested in what you think about them and maybe some ideas to improve them.

2 Pirate:

Choose a color and gain one piece of Gold for each district of that color in any player's city. Districts of that color in the city you chose can't be gained gold for again for the rest of that round.

2 Slave trader:

Sell a district card from your hand to the bank or a player of your choice (they have to buy it) for halve its value (round up)

3 Warlock:

Gain a card for every character who already drew cards in that round. For the rest of that round :Whenever a player draws 2 or more cards gain one of them(for the normal drawing it's the one that would normally be thrown away). If so, you can discard 1 card to choose which one you get. Otherwise the drawing player decides.

5 Inquisitor

Gain gold for blue districts. Name a character. From the beginning of the next round until a new character is chosen by the inquisitor, that character is out of the game.

7 Scientist

You may not build during that round. You may first exchange Gold for cards and then cards for gold.

9 Jester

Gain one gold for every district of the color you have the least amount of districts of (except those colors you have none of) . You may give one of your districts a color of your choice(Therefore districts can be ordered to show which ones belong to the same color).

?-Characters

Those aren't announced by the king but appear under certain circumstances. They do not conduct their own turns (except the actor) but have just their effects.

? Actor

You may reveal the actor when any other character is announced and actually in this game.(So another player revealed the card) After their turn you make an additional turn as that character except you don't get your 2 cards or gold.

? Executioner

Same condition as actor. You may offer the player to give you 3 pieces of gold, 3 cards or one of their districts costing up to 3. If they don't want to give you what you chose, they lose their turn.

? Saboteur

You may reveal this character if someone builds a district in their city. Destroy it. Then cards from the drawing pile are revealed until a district costing 1 gold less appears which is then built instead of the one one you destroyed. You may enlower the costs of the "replacement building" by paying an equal amount of gold to the bank. (So, if you destroyed the Laboratory and pay 3 pieces of gold the player gets a district costing 1.)