Fics like Is This Upgrade Permanent?

After Ben turns into Upgrade and merges with Rex, there are some unexpected consequences that leaves Ben trapped in Rex's universe.

You may also like

1. Gwen X by NullnLight (Ben 10 Series)
2. Keep the Charm But Don't Break My Heart by UnknownUncut (Ben 10 Series)
3. A & O x1 by RecycIedTrash (Generator Rex, Ben 10 Series)
4. Dark Mirror by Acidwing (Ben 10 Series)
5. Ben 10 sols by Mina%20The%20Hollower, TheTrueMcCharles, minahollow (Ben 10 Series, 九日 | Nine Sols (Video Game 2024))
6. Ba ba black sheep by Charcoal_pencil (Ben 10 Series)
7. My Name Isn't Ben by B1ack0ut (Ben 10 Series)
8. Zennia Tennyson: Accidental Conqueror, Useless Lesbian, Part Time Galactic Hero by CyberQueen_Jolyne (Ben 10 Series)
9. THE WEIGHT OF TWO WORLDS by IMFanatic (僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia (Anime & Manga), Ben 10 Series)
10. Mitosis by VoidInkedPen (Ben 10 Series)
11. Protection Over Everything by RecycIedTrash (Ben 10 Series)
12. Light by Kippydog (Ben 10 Series)
13. Overwritten by Kippydog (Ben 10 Series)
14. An All-New Omniverse by Zayden_StormVoid (僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia (Anime & Manga), Ben 10 Series, more)
15. Book 1 - A Kingdom of Two by justme2102 (Danny Phantom, Ben 10 Series)
16. The Warm Routes by Wolak14 (Ben 10 Series)
17. Beyond the Dust: The Hero of Heroes by Archie_Leo, DraugrSlayer17389, Iorweth, Morijingod, Trickster1 (Ben 10 Series, RWBY)
18. Fairy Tail Reacts to Ben 10 by Anonymous_WriterOfWriters (Fairy Tail, Ben 10 Series)
19. Transformative Spirit by Picaro92, VannyStar (Ben 10 Series)
20. Green Heart by Picaro92, VannyStar (Ben 10 Series)