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1. Alone Together, Across the Multiverse {Old} by WolfGod369

   Fandoms: Undertale (Video Game)  

   • Explicit
   • Graphic Depictions Of Violence
   • F/M
   • Complete Work

   12 Sep 2026

   Tags

   • Graphic Depictions Of Violence
   • W. D. Gaster/Reader
   • Reader
   • W. D. Gaster
   • Other Undertale Characters
   • Other Additional Tags to Be Added
   • Tags May Change
   • Scientist W. D. Gaster
   • W. D. Gaster is Papyrus and Sans' Parent
   • W. D. Gaster Needs a Hug
   • Goopy W. D. Gaster
   • Reader-Insert
   • No Use of Y/N for Reader-Insert
   • Gender-Neutral Reader-Insert
   • AFAB | Assigned Female at Birth Reader-Insert
   • Reader Is Not Frisk (Undertale)
   • Nonbinary Chara & Frisk (Undertale)
   • Undertale Alternate Universes
   • Reader and Gaster Eventually Get Together
   • Slow Burn
   • very slow burn
   • Fluff
   • Romance
   • Tags Contain Spoilers
   • Graphic Description
   • Implied/Referenced Torture
   • Suicide Attempt
   • Implied/Referenced Suicide
   • Panic Attacks
   • core!Frisk
   • Reader Has a Purple Soul (Undertale)
   • Ecto-Tongue (Undertale)
   • Biting
   • Oral Sex
   • Vaginal Sex
   • Soul Sex
   • Orgasm Edging

   Summary

   Gaster searches the multiverse for the scattered pieces of his Soul, finding that you (the Reader) are somehow bound with one such fragment. Forced to take you with him, you slowly bond over time, traveling the multiverse together on your now-shared mission. What starts out as a tense relationship gradually evolves into an actual relationship with the former Royal Scientist.

   This is the OLD version of this fanfic. I'm currently rewriting this into the NEW version - posted under the same name, but with {New} in the title! ^v^ It's part 2 of the collection.

   Series

   • Part 1 of Alone Together, Across the Multiverse

   Language:

   English

   Words:

   132,855

   Chapters:

   29/29

   Comments:

   2

   Kudos:

   7

   Bookmarks:

   1

   Hits:

   163