In the recent story of Dragon Ball Super, the present Zamasu has been killed by Lord Beerus but is still alive in the future. It has been told that Goku Black is Zamasu in Goku's Body, while Zamasu is the one from the past. All these things seem messed up. Can anyone provide a simple explanation of how all this timeline stuff works?
It all starts with Trunks in the Android saga
Future Trunks lived in a very bleak future and was backed into a corner with Gohan's death and his Super Saiyan transformation not being strong enough to stop Android's 17 and 18. So in comes the time machine to go back and save Goku from dying from a heart virus.
When Trunks travelled backwards through time, he created a branching time-line. Let's call the present world World A (where Trunks pwns Mecha-Frieza) and the other world World B (Androids wrecking s***). Now nothing Trunks does in either world affects the other because they are two separate time-lines.
Because Trunks broke the taboo big-time by going backwards.
Fast Forward to Dragon Ball Super
Now in DBS, Buu was never revived in World B because Trunks killed Babidi and Dabura due to a power buff he got from training with Supreme Kai and Kibito with the Z-Sword. However, it is revealed in the manga that the battle with Dabura took a heavy downturn, as not only did the Z-Sword get turned to stone and obliterated (eg. Grandpa Supreme Kai sealed within it was killed), but Dabura killed Kibito and Babidi killed Supreme Kai.
We already know that no Supreme Kai = no god of destruction aka no Beerus because their existence is a set. Which also equates to no Whis because Whis is an angel that exists solely to serve the god of destruction. This also means that the Potara Fusion and Elder Kai unlock ability are non-existent in World B.
So looking at the Gowasu in World B, it was shown in the anime that he was murdered by Zamasu who took a time-ring and collected the Super Dragon Balls and wished for Goku's body.
With that time-ring he went to the past of World B.
This is where things get icky
Because Black did reverse travel like Trunks, he made a new time-line. In this World C he was still plain old Zamasu but was planning to kill Gowasu as he had just sparred with Goku.
Black killed Gowasu for a second time and influenced his past self to join him. This World B past tense Zamasu collected the Super Dragon Balls and wished for an immortal body. With that, immortal Zamasu got a new time ring from Black's reversal which allowed them both to go back to World B and kill all the gods of each universe in that timeline.
The real kick in the chops
So Beerus found out, got mad, and killed Zamasu in World A. That means nothing for two reasons: first, Beerus' actions do not matter in this world because Trunks already separated the timelines way back in Dragon Ball Z; second, even if by some stretch of imagination God's affected the time-line differently, it does not matter because of the power of time ring.
THE PLOTHOLES HERE ARE GAPPING ONES
- What happened to universe C?
- What happened to Earth in universe C? Since in that case there would be 2 Trunks (I have no idea what the plural of Trunks is).
- Why was there like 5 time rings in the episode that Gowasu revealed them? Trunks has not jumped back and forth 5 times. Or has he? Also, what's the difference between a green ring and a white ring?
NOTE: This is why when anime delves into multi-verse, time-travel stuff, it always turns out bad unless it's Steins;Gate. <3
EDIT: Finally complete!! Getting all those screenshots was a hassle but I think my answer is as thorough as it can get.
You got the worlds mixed up, World B Zamasu never met Goku and would have no reason to use the Super Dragon Balls to wish for Goku to switch bodies with him, it's Zamasu from the world created when Whis used his temporal do-over to go back so Beerus could kill Zamasu before he killed Gowasu. From Zamasu's point of view he killed Gowasu with Beerus and Whis thinking they'd killed him, no one was there to stop him from gathering the Super Dragonballs and wishing for Goku's body which he envied after sparring with him in universe 10 and using the time ring created by Trunks splitting the timeline to tell Goku about the Androids as that world had no Supreme Kai and therefore no Beerus, who was the only one with the will who powerful enough to stop him. He then went around and killed the Supreme Kais of the other 10 universes (He'd already killed Gowasu and thus universe 10's god of destruction)
Once in Future Trunks' timeline he met up with the Zamasu of that Universe and helped him kill Gowasu and gather the dragonballs and wish for Immortality and then a year later, wish for the Dragonballs to be destroyed.
Green ones are the alternate timelines created. White one is the original. It would be interesting to see if someone will find a Goku from another timeline (when he was saved by Trunks and prior to Trunks returning) to fight this Goku. Obviously, Goku is the key player who screwed it all up when the heart disease didn't kill him.
So strictly speaking the original and unaltered timeline is the future Trunks came from the first time, with a dead by Heart-attack-Goku, everyone killed by androids, then Trunks destroying the androids and eventually being killed by Cell who abandones the timeline afterwards, i.e an Earth with no superbeings at all. So Kaioshin has no one to hire for stopping Babidí.
Cell travel forced Trunks to stay in present time and train with Vegeta so he forged a diferent future were he stomped everyone (even Cell) until Black appeared, this fucked-up time-line was eventually erased by Zeno-sama.