First thing to do, is get rid of your pre-conceived notions that you're being thrown to "lions" which seems to me that you're assuming the kids will be terrible to you or hate you right off the bat. You can't know that at all.

As for what to do, kids are kids, they will treat you with respect as long as you show them some first. I could write a long description of waht to do in your situation and I'm not saying i'd be right about it all but it's such a complex situation you're getting into, there are far too many factors involved.

Depends on the kids, the relationship with the dad, and so many other factors. There is no easy answer here really.