You'd play my daughter/noece who had a baby about 6 months ago with a man no longer in the picture. You're staying with me and my wife while raising the kid. With you being around and nursing a lot I've noticed how much bigger your boobs are and I start feeling attracted to you. One day my wife takes the baby out shopping to give you a break and you take the opportunity to pump milk using a machine. It's then I incidentally find you and spy on your. From there we could either go in 1 or a few directions

1) You notice me spying on you and while disgusted at first, however your pent up sexual tension and taboo nature of it all is enough for you to give in to me

2) You notice me spying on you and you instead pretend not to notice me and start to tease me hoping I will pounce on you

3) You don't notice me and it's a slow burn of me flirting with you and giving out sexual innuendos until you eventually decide to fuck me

4) I can't contain my lust for you and I force myself into you over and over until you fully sumbit to me