In Assassin's Creed Odyssey (ACO or AC Odyssey) you have the option to beat and recruit NPCs to join your ship crew. If the common opponents have no special characteristic, the elite soldiers and officers are already more attractive
However, there is a class of opponents even more interesting in terms of skills: The Mercenaries. Early in ACO, you'll have the opportunity to track down and eliminate mercenaries with various attributes. But why kill them when you can convince them to work for you?
To easily obtain effective lieutenants, start by hunt down a mercenary and then observe him for a few moments with Ikaros, in doing so, you will reveal his level of "rarity" (in general, epic or legendary) as well as the advantages that he will be able to offer you.
After that you can use your fists or a Sparta kick to knock him out. You can then recruit and assign him as a lieutenant.
Recruit Gelon - Special Lieutenant
Quest: Crewless Side quest
Reward: 3300Xp + new lieutenant
To unlock or recruit Gelon as Lieutenant you have to complete the side quest “Crewless”
Go to east coast and meet Gelon to activate this new mission. Once this done, go to the Southeast and use Ikaros to locate the places.
After that, dive in the indicated place and search the corpses to retrieve the Gyke’s bracelet. Once you collected this item, search the vault in the vicinity before going back to the surface.
Then you can attack the camp located not far from there and loot the chests to get the valuables. From then on, you can go back to Gelon and offer to come to your service to complete this side mission.
Recruit Tekton - Special Lieutenant
Quest: A Pirate Life
To recruit Tekton as Lieutenant you have to complete the quest "A Pirate Life".
Go to the small island southeast of Phokis and meet Tekton to activate this new quest. After that, head towards the pirate hideout located southeast of your position.
There, locate the places then eliminate the opponents, then free the brother of Tekton before taking him to a safe place. At the end of this sequence, you can return to the carpenter and decide how to complete the quest.
Tell the truth (1890Xp + new lieutenant)
If you reveal the truth about the fate of his brother to Tekton, he will agree to join your crew despite his grief.
Lying to Tekton (Failed quest + 1417Xp)
If you choose to lie to Tekton, he will leave your ship and you will never see him again. And although you still get an experience bonus for your efforts, the quest will fail.