Let the mafia pick who the town traitor is. This might seem extremely overpowered and it seems like a "conversion role", but it's better than having the Town Traitor assigned randomly at the start of the game. Though, this could be balanced by forcing mafia to give up their night kill to convert or forcing all mafias to visit the traitor. Letting mafia choose the Town Traitor will force players such as a Jailor or Mayor to stay hidden so that they aren't converted. In addition, Mafia won't get undesirable players on their team. Overall, letting mafia pick their Town Traitor will be beneficial because it forces both factions to play more strategically.
Possible ways to implement this:
- Either Godfather or Mafioso can have a night ability and select themselves to choose whether or not their target will be converted that night. Instead of attacking their target, they will convert them instead.
- Give Godfather or Mafioso a day ability to convert someone into a traitor
- etc etc
These are some broad ideas, specific interface system should be left up to developers.