Assassin’s Creed Odyssey will let you act however you like. You won’t have to be a protector of the people any more – since Alexios and Kassandra are both mercenaries, you’ll have the freedom to be a criminal if you want to. Acting like a complete bastard will have consequences, though. When you step over the line, an NPC you wronged may put a bounty on your head. If this happens, other mercenaries will start hunting you, and they won’t stop until you’re either dead, or in jail.
According to the developers, when you start a playthrough, the game will choose 50 mercenaries from a deep pool of both hand-crafted and procedurally generated soldiers. When you commit a crime and get a bounty on your head, some of them will start looking for you. Whenever you raise an alarm, mercenaries will be dispatched to search the area. The higher the bounty, the more troublesome the mercs.
They’re supposed to be on the same scale of challenge as AC Origins’ Phylakes, only you’ll never use them up. If and when you slaughter the 50 you’ve been assigned at birth, the game will just keep reaching deeper into the pool in order to supply you with more. The bounty system will be similar to the wanted mechanic in GTA – the more damage you do, the more stars you’ll get.
If you’re the confrontational type, you’ll probably want the bounty, so you can fight stronger enemies and get better loot. If not, you might want to look for the person who started it all and deal with them. Once you’ve defeated a mercenary, you’ll have the option to either kill them, or recruit them as a crew member for your ship. You’ll get their stuff either way, so it’s just a matter of additional manpower and roleplaying.