Next time you talk to him, he’ll give you the Curl Up gesture. When you return and talk to him again, he’ll offer to go out and pillage. You’re free to let him go, and he’ll be back after you defeat the next boss. Greirat will offer to pillage again after you discover Irithyll. However, in order for him to survive this trip, you have to progress Siegward’s questline and make sure to talk to him at the kitchen in Irithyll right past the sewers with the spider ladies. Once you speak to Siegward, let Greirat pillage, and he’ll return safely after you defeat the next boss.
He’ll offer to pillage once again when you’ve discovered Lothric Castle after defeating the Dancer of the Boreal Valley. Do not let him go out, as he will not survive this trip no matter what.
Be sure to check out our Dark Souls III wiki for more tips and tricks.
