You need to understand what happened in the original fanfic first before you can read this extra (what should be obvius but there's always stupid people out there. ahem.)
In the original fanfiction Rimuru and milim had to fight because Milim was controlled by another demon lord. After their fight Rimuru and Milim confessed their feelings for each other and that was basicly it. There was one scene at the end where they had a child and where married, and because of requests on both this, and other platforms, i'll go make a extra with the marriage and the marriage night. (Meaning i'll go and write my very first sex scene. Since it's my first, please don't go to hard on me okay? Thank you.)
Also i have no idea about marriages because i always rejected invitations to marriage ceremonys. (I'm currently in a state of regret), so i'll don't know if this will be any good. I have a basic idea through films and stuffs, but i don't think i'll be good at it.
Edit: I forgot to tell you where the story actually starts so here we go!
The Story starts shortly after Rimuru and milim come back from. Whatever you can call it. So it's like a story that happens between them returning to Tempest and the timeskip where the story ends.
Extra Info:
I'm writing this so i can upload this now. I will start writing the actual fanfic start of next week and will upload it as soon as i'm done so please look forward to it.
Have a nice day. Bye!