So I'm writing a Umbrella Academy Au were Diego is Five's biological Child, and you know how Lila wanted to test to see if he was good dad?
Well that got me thinking, in this Au Diego doesn't tell the family about Five keeping a secret since he doesn't want Reginald to know, then after he left and started taking care of Five full time due to plot reasons, he didn't tell his family cuz he was trying to distance himself from everything.
So in the start of season 1 Klaus and consequently Ben are the only ones who know about Five.
So y'know big reveal yada yada, and at some point it is discovered that Diego Trained Five.
(in this Au kids of people that have powers also have powers, so Both Five and Clarie have powers, though in the start Claire hasn't developed them yet).
And everyone is raving about how Diego is a bad father and how he is just like Reginald.
(Diego takes some of this criticism to heart as he was always worried he would be a bad father)
But then some thing happens, Five gets hurt and Diego goes in protective dad mode, in which his focus is getting Five out of the situation, not ending the fight or killing the guys, his priorities were getting Five to safety, he stitches Five up and comforts him as this is basically a civilian Child, with the 1 caveat that he has powers.
At some point someone probably Luther pre-himbo starts saying stupid shit about how they are a team and you have to follow orders yada yada.
Five apologizes for "getting in the way and being a burden"
(this has a little trauma causing from his mother's side of the family, little backstory as why Diego has sole custody)
But Basically Five feels bad for not helping even though he has powers and could have gotten both himself and everyone out of there safely.
Diego just cuts him off, and as pissed as he is at Luther for pulling rank right now he ignores it because Five is his priority.
Tells Five that he not a burden, that none of this is his fault, that he shouldn't apologize and that him having powers doesn't mean he has to use them, reminding Five of what he explained to him when he was "training" him.
(the word training mostly only being used because of when Five first got his powers he was in a phase of wanting to be a secret agent and Diego decided that while also teaching Five how to use his powers safety he could make it a game so that he doesn't feel forced or pressured into doing it)
That his only job is to be a kid, Diego is the adult, he the one that has to worry about the big things, he reminds Five that he taught him how to use his powers because he had absolutely no control and would hurt himself pretty consistently.
(while also not wanting Reginald to hear about a superpowered kid and taking Five to be taking to become the 2nd gen of the Umbrella Academy as well)
That's when the family (sans Klaus and Ben) realize that no Diego is nothing like Reginald, that Diego love his kid.
(to be fair them saying that is mostly them projecting their fear of being like Reginald whether they know it or not but that's for the apologies part)
Yada yada they talk and cry everyone has a happy ever after.
And years later when Allison is struggling to teach Claire to use her powers, it's when the karma sets in as she uses the same tactics that she criticized Diego for, and it still doesn't work.
(In the end Five is the reason she learns, mostly cause I think it would be funny)