Hey ! How are you ? So I have a question for you... ( mostly because your metas on Hufflepuff!Scott and Slytherin!Stiles are awesome and because I was rereading winter wolves), Where would you sort Steve and Tony ? I love your blog <3
My answer's gonna be a little short this time because Adulting™, but tl;dr, Steve I see as a Gryffindor/Hufflepuff Hatstall, and Tony as a Ravenclaw/Slytherin Hatstall. The biggest dividing line is Civil War.
We know that prior to Rebirth, Steve was a little more aggressive to make up for his small size and ill health. He would go through any lengths to do what he believed to be right (though was also not above trickery). He's never afraid of "toil" - one of his key characteristics and the ways people identify him is that he never gives up, that he "can do this all day". But, while he strives to be just, he is not diplomatic, nor particularly "fair".
I can definitely see why people put him in Hufflepuff - and I've put him there myself in my embarrassing first gifset - but Civil War, to me, tips him over from Hufflepuff to Gryffindor.
All his behavior in relation to Bucky and Wanda was the pursuit of justice - at the expense of fairness (and for a variety of reasons, while he might have been pursuing justice, I think he failed pretty spectactularly, but that's a rant about Civil War's writing, not Steve nor his House).
Now, Tony does strive for diplomacy - which is the biggest reason Tony could be a Slytherin. We use the word "politician" as an insult a lot, but people like to dismiss/forget that leaders and diplomats are also politicians. Diplomacy is, fundamentally, a form of manipulation. Tony is predominantly a Ravenclaw because of his intellect, but he has a great skill for reading people, and manipulating them for a good cause. He is tremendously empathetic - his empathy for the woman whose son died in Sokovia in AoU is why he threw in for the Sokovia Accords in CACW, despite the fact he was in the same position as Steve to lose a lot and be at risk under them.
But, he does all this rationally. He is still fundamentally a man of intellect, and does not make decisions based on his gut or his heart, but his head. In fact, his biggest mistakes were usually due to what he did when he felt something/operated on the basis of his feelings instead of his rationality. The most obvious example is CACW - throughout the movie, even when he was playing the antagonist to Steve, every decision was reasonable and rational. He wanted to bring Bucky in when they thought he'd bombed the U.N. - but as soon as he was presented with evidence that he'd been wrong and it wasn't Bucky at all, he turned around and sought to help Steve and Bucky; that was the rational decision. But when he found out the Winter Soldier killed his parents, and attacked Bucky for it - that was irrational.
So I can definitely see the basis of Slytherin!Tony, and he would've been one hell of a hatstall even at 11...but I still think he's a Ravenclaw at heart. A very ambitious and diplomatic/political/manipulative Ravenclaw, but still a Ravenclaw nonetheless.