Reading all "kill the fission duplicate, end the power, and revive the duplicate via revivify or psionic revivify" stuff online, it made me realize that Fission's rejoining effect at the end of the duration is an overt action by the power to merge the two of you back together, and the timing is one time only and can be dodged.
So if you dodge the timing by manifesting Time Hop, is your duplicate permanent? Dodge the timing by
- Duplicate manifests Time Hop
- You dismiss Fission, ending it and forcing the rejoining effect to occur.
- Duplicate time hop ends.
or, if the DM thinks the duplicate has an active "fission" effect too,
- Manifest Time Hop yourself
- Duplicate's Fission duration lapses.
- You reappear.
When the duration expires or when you dismiss the power, you and your duplicate rejoin, no matter how far from each other you are.
If you hop forward in time, you don't exist. This is not a difference in distance right? Which means Fission has no ability to rejoin you because you or your duplicate is out of the power's reach.
On a side note,
All powers affecting a fissioned creature, either the original or the duplicate, end when the fission ends. All damage, including hit point damage, ability damage, ability drain, and ability burn damage, is added together.
Does this part of the effect happen to you? to both of you? to none of you? Does Time Hop let you dodge this?