I'd argue that sirens would hit the current pacing due to them needing to reach the Isle and get the item that El Coyote needs before the time limit, so I'm not sure if there's time to create the needed build-up for a scene with them.
Not to mention that it wouldn't make sense for Orion's character development. Remember, his target milestones are that he needs to come to terms with the role that the dead thrusted upon him AND he needs to realize that he loves all the girls equally and that he wants to take his relationship with them seriously. Thus, he needs to stop thinking about banging every new hot chick that he sees and start moving forward towards his goals because the dead don't need that shit from their chosen champion.
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