Stony where tony gets drugged at a party. steve takes him home to sleep it off and keep an eye on him. but on the ride home, tony is crying and begging steve to forgive him, that he doesnt know what happened. he didnt mean to drink.get drunk. and steve is surprised and confused. he tells tony its okay, he just needs to rest and he will be better, but tony just cries and begs steve not to leave him, or worse; take him to rehab. he promises he will do better, and wont ever drink again. steve tries to clarify, but then he realizes that tony’s drinking problem was worse than he(or anyone)thought. he realizes tony was an alcoholic, and pepper shipped him to rehab, but he had a shitty experience, but after that he never drank again. steve, who at this point loves tony, but is not with him, tries to remember the last time he has seen tony have a drink but he cant remember. cue steve realizing how tough shit is for tony, and just cuddling him and helping him through the night/until the drug wears off. tony cries in his sleep, that he promised he didnt drink, and he whimpers almost all night. steve just holds him and reassures him as much as he can.
the next morning tony wakes up feeling hungover, and dirty, and emotionally drained. steve helps him shower, maybe even gets in with him, and then someone brings them breakfast to eat in the room. steve asks tony about it and tony just decides to be honest.
he tells him how in his twentys he did a lot of drugs, and he drank a lot. basically he had a lot of issues and he thought he could drink them away.eventually, he hired pepper, and after she saw him sneak of to snort some coke, she had him shipped off to some fancy rehad, but tony had a bad time there for reasons i will think of later. he got sober, and has been since then. lets pretend this happened when he was 28. and he met steve at 29, but his reputation precedes him.
steve believes him, of course, and talks to him. they cuddle and hug and from this they start a relationship.
that night, they join the rest of the avengers for diner and a movie, and during the movie tony falls asleep on steve. steve doesnt even hesitate, and he picks up tony to take him to sleep. one of the avengers asks if his intensions are good. he basically growls and returns the question, because the night before they didnt know he had been drugged, and treated him shitty because they thought he was drunk and didnt believe him when he said he hadnt had any drink. they are ashamed, but agree. steve tells them he loves tony, and wants to take care of him and love him forever, before making his way to tony’s room and tucking them both in for the night. safe and warm and loved.