Happiness by Three Days Grace.
I don't know what this is. I just had Tony feels and had to write them.
It didn't start out as a craving, didn't start out as a need, didn't start out as anything other than the simple fact that Tony wanted a drink and the only thing he had on hand was an old bottle of his dad's whiskey, and from that first sip he was hooked. Pepper swore up and down that she should have binned the bottle when she had the chance, but she never really had the chance in the first place. And really, when the whole mess started, she didn't mind because Tony was happy, the cursed chemicals he poured down his throat stimulated reactions with other chemicals within him and those reactions made him happy. But that all stopped when he realized the thing he needed to stay alive was killing him.
None of them are sure whether or not he wanted to kill himself from alcohol poisoning before the Palladium had a chance, but one thing they do know; the more the pressure of succeeding slammed down on Tony's shoulders, the more his drinking increased. Pepper learned very quickly that a stressed Tony was a desperate Tony, she learned that a desperate Tony would do anything and everything to succeed, but she also learned that a desperate Tony was a Tony who drank alcohol like it was water, but she hadn't learned how to separate the two, not then.
The media hounded Tony's every action in the public world and constantly tested themselves against JARVIS in their vain attempts to get into his private life. They criticised everything he did and just had to have the last word on anything where he was concerned, if only they knew, but they'd just criticise him for that too.
It was Coulson's death and the events with the missile and Loki and the entire Avengers ordeal that tipped him over the edge, he sank into his work and drowned in his drinking and they slammed the label of PTSD over his head and he let them. As long as he had his alcohol he didn't care.
The Avengers learned quickly too, they learned that a depressed and suffering Tony was an unstable Tony, they learned that an unstable Tony was a Tony who drank to excess because swallowing the burning chemicals was easier than swallowing real life. They learned that no matter how hard they tried, the alcohol would always be able to do something they never could and that was provide Tony with a few hours of blissful happiness and total oblivion. They learned that a sober Tony was far more dangerous to himself than a drunken Tony and they would never be able to understand that, and Tony didn't care, he had his alcohol, it burned away all the stresses in his life and left him with peaceful oblivion and that was all he wanted. Happiness straight from the bottle, because real life was too hard to swallow.