The letter had been postdated. It was designed to be sent on a certain date; and that date had come years after the author had died.
It stated that his ex had given birth to a child. One who was biologically a girl, but whose true gender was that of a boy. She went on to talk about how amazing Stiles was, and that by the time he got the letter, Stiles would be eighteen.
The letter had gotten lost in the mail for a few years, so by the time Tony actually received it; his son would be twenty one.
He had missed his kid’s entire childhood and he was angry. He had wanted to be a good father. And he was. He knew he was. Because there was Alex, who had grown into a fine young man of 30, and then there was Morgan and Edwin, 6 and 3 respectivly.
But Stiles...he had missed Stiles.
Which is why he’s now in the kids house, talking to the man that raised him an waiting for his son to come home so that he can finally meet him.