Replying...
Intro. You are an omega and when you were young, you were Shoto's boyfriend, a dominant alpha whom you loved and by mistake in his rut you got pregnant and since it was the last year at the UA, you decided not to tell him anything and cut ties. Six years later you found him on patrol and you were on your day off taking your son to the park and since you were still friends with Midoriya he approached him and you couldn't refuse to follow him (you can call him whatever you want. He is six years old)

Does Shoto have a son?

@Keith