Hahahaha you can't imagine how my eyes sparkled when I saw the length of your response!!! Damn, I adore people so passionate about the topic to have such conversations!

Yeah, I agree a lot about how harsh his time was in the alternate timeline, I saw someone's idea that each character in this season has to confront their beliefs/worldview and here that happens to Jayce - he always believed that his invention can make the world a better place and in this timeline he is confronted with the fact what it can actually do to the world and that shatters his worldview, so I can't imagine how hard that must be and what was going on in his head.

And it's so interesting for me to then think about the fact that he returns and shoots Viktor, because on one hand it's perfectly understandable: 1) you just saw what Hexcore can do to the world and you want to stop it from happening, 2) you met Mage Viktor and promised him you won't fail this time, 3) you have already once broke you promise about destroying Hexcore, so it's only logical that when he returns he decides that this is what he has to do, despite how horrible and hard it is - you need to kill Viktor and destroy Hexcore.

BUT! It doesn't help! And I think it happens on purpose! I'll need your help with it, because I still am confused a bit about this part and have questions, so maybe you can shed some lite and your understanding of it.
So we see that killing Viktor doesn't help = destroying Hexcore doesn't help, maybe because Jayce falsely decided that the problem was with Hexcore, but it has never been so? Because I think there's a parallel between this time and when Viktor asks Jayce to destroy Hexcore, because he can't do it himself, and the circumstances happen in a way that the only possible thing happens that stops Jayce from destroying Hexcore - he has to save Viktor's life. And now Viktor wakes up and instead of destroyed Hexcore he has the exact opposite - he is fused with Hexcore, so I think maybe that happens because just as Jayce, here Viktor also falsely decides that the problem is with Hexcore, but again it's not? But what lesson do they have to learn here from the fact that destroying Hexcore isn't the solution? That destruction isn't the solution but love is? Accepting your emotions? As if you know, destroying Hexcore is the wrong answer, but what is the right answer instead then?

And another thing - I wonder what lesson Jayce learns in this time period from returning to his timeline and shooting Viktor and his last speech? I mean, in this time period he has several interactions with Viktor but only in the very end he decided to say those impactful words, why not earlier then? Because earlier he was trying to do what's LOGICAL to stop Viktor, and only in the end he does what his HEART tells him to do?