I’m going to do a Miss Manners thing here and propose a rule of etiquette.
If you’re in a couple, don’t start fucking one of your partner’s children. No, even if that child is adopted. Really. That’s a rule. It’s a good rule. Follow it.
No, even if that child is no longer a minor. No, don’t stay with your partner waiting patiently until that child turns 18 and then pounce.
No, even if the child says you were never a parental figure. Even if you were always buried in a newspaper or playing a video game whenever that child was in the room – even then, don’t start fucking that child.
Are there exceptions to this rule? All rules have exceptions; there must be exceptions to this rule. Are there?
No.
No, this is an exceptionless rule.
But what if you go on to marry your ex-partner’s child? Is it ok then?
No.
But what if you marry your ex-partner’s child and the two of you adopt children. Then it’s ok, right?
No.
No, it’s not ok if you marry your ex-partner’s child and the two of you adopt children. What’s more, somebody should keep a close watch on those adopted children. As many people as possible should keep an eye on those children. That’s doubly or triply true if those children are the same sex as the parent who is the child of the ex-partner. Everyone involved should be alert to patterns. But that is only damage mitigation; the rule is don’t start fucking one of your partner’s children; if that rule is obeyed then the damage mitigation will not be needed. Just don’t start fucking one of your partner’s children. It’s a simple rule.