#so obviously

So he starts slowly warming up to this kid, allowing himself to get close and talk to him and eventually even hold him.

And baby Kaeya is so relieved, because he thought his brother had grown up to hate him but maybe everything in the future will be okay. Baby Diluc also starts to feel better because he really didn't like that this bigger version of him was glaring at his baby brothers. (Protective Diluc for the win!)

Crepus doesn't consider himself the smartest man, but he knows that something's off with his boys. They tell him a rather obvious lie about not seeing him in sometime because he went on this grand expedition with Varka. But he could see the distraught in his boys eyes when they looked at him, like they'd seen a ghost.

So of course Crepus makes it his mission to make all four of his boys get along perfectly, not only does he want them to like the other brother, but he wants his boys to feel good about their past/future selves. Because if he isn't going to be around long enough for his boys to grow into men, he's going to make sure that they're alright while he's here.

He also sits the older boys down and talks to them. Kaeya's first, because even though Diluc he's outwardly grumpy, Kaeya's mask is so obvious and laid on so thick it's scary.

He tries to coax the truth out of Kaeya first, to understand what's wrong before he makes it better, and archons it hurts to hear Kaeya calling him "Master Crepus" instead of dad. Eventually, he can't take it anymore, he tells Kaeya that he knows the boy is Khaenri'ahn and he doesn't love him any less for it. That he's sorry for being the second father in his life to leave him and all he wants is for Kaeya to understand just how much he cares about him.

And Kaeya can't handle it. He tells Crepus he's a spy, and whatever else he thinks he has to to make the man hate him. It doesn't work of course, because Crepus loves him so so so much and nothing would ever change that. And they cry, and they hug. And the next time little Kaeya sees big Kaeya he feels just a little bit better, because he's always been observant and he knows something just changed for the better.

Then Crepus talks to Diluc and its surprising just how quickly Diluc breaks down, apologizing for not being able to save him and do better. That he's sorry for breaking their family apart and how he wishes he could change. Because Diluc has a deep rooted fear that everything that has ever gone wrong in his life is his fault and he's never doing anything right.

Crepus tries his best to reassure his boy that nothing was ever his fault and he was also just a child so how was he supposed to do it all on his own? Then Crepus finds out how he died, how Kaeya gained his vision and everything that happens after. After so long of keeping everything bottled inside, spilling all of his secrets to a long-dead ghost is the one way Diluc feels he can lift the weight off of his shoulders.

And Crepus is distraught, distraught because he knew, knew he should've gotten rid of the damned Delusion long ago, that he never should've taken it in the first place. It's all his fault that their family fell apart and now he needs to fix it. So he promises Diluc that he'll never touch that delusion again except to destroy it, and actually does so in front of his boy. Diluc is so, so relieved and afterwards he goes to Kaeya because that is one last thing he needs to get right.

Diluc and Kaeya have the most heartwarming heart to heart ever, finally letting themselves be fully honest with their feelings and even though their relationship isn't healed, it's on the path there.

Then Albedo appears (because I love him) and explains some things to them.

1) Time travel isn't technically possible, at least not in both directions. If one person travels back in time, another can't travel back to that same past with the person because the timelines have diverged and some other nerdy crap I just realized I don't feel like explaining

Point is, timelines diverged, they didn't change the past but did change the path of this Universe's future, and that was how Albedo was able to find them and bring them back. The entire ragfam is grateful for this alternate universe people fixing their lives and our Diluc and Kaeya go back Adelinde a visit with an apology cake