There were days when the realization that he was someone’s father made Steve's head hurt. Mostly he was grateful that he could trust his instincts, because Peter was what had been missing from his life. Yes, he still had lingering, unresolved issues from his time in the Army, and sure, he had what Bucky annoyingly referred to as a criminally untapped ass and no life outside of work and Peter, but Steve was okay with how his life had turned out because of trusting his instincts.
Unfortunately, those same instincts had straight up betrayed him by going absolutely haywire upon being exposed to Tony Stark.
Veteran single dad Steve runs a tattoo shop. For his 40th birthday, Pepper arranges for Tony to get that tattoo he always wanted, and he winds up with the mother of all crushes instead. Jumping out of airplanes is one thing, but falling in love is something else entirely. Steve struggles with the idea of actually letting someone into his life. Tony is left trying to keep his heart from being broken while Steve figures things out.
After Siberia, Tony held it together, but after that awful letter he started drinking. Heavily. And now he's having blackouts. Obviously, he doesn't remember calling Rogers on that cursed phone. And what you can't remember, well, it didn't happen. Obviously.
The first time Jarvis holds little Anthony in his arms, he is overwhelmed by emotion that is surprising in its intensity. When little Anthony's palm curves around his finger, Jarvis ducks his head to keep the others from seeing the wetness in his eyes.
"Hello Master Anthony," he whispers into the little ear, tugging the bundle of blankets closer to his heart.
Tony couldn't hide the bruises and injuries forever, pretending like nothing was wrong. One of these days, Tiberius was going to really lose control, and Tony would be lucky to survive. Eventually someone would have to notice.
Tony takes the bullet meant for Captain America at the end of their war and through his death, brings together the team again. Only, he isn't really dead and when he comes back, the equations between the team-mates begin to alter and reform, writing a new story altogether.