You're referring to Arkanis Gath, not Artemis Entreri. You can only get Artemis Entreri if you spawn him in the game using the following command:
CLUAConsole:CreateCreature("ARTEMIS");
Then use Ctrl+Q on him. Him and all others earn XP like any NPC, but he will not have any dialogue and you will have to find a funky portrait for him.
Another one you can use is Ctrl+I, you may need to do this a few times. Makes them talkative.
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