I don't like discussing politics with anyone - and T mentioned something very very very miniscule regarding it (not even enough to tell which side she was on) and I was just like ...ugh. Besides that, we've talked about religion, intercourse, illicit drugs, self harm and way more and she's been very good about being open to the conversation. So i'd just limit politics but honestly - if you trust your T enough I don't see why you shouldn't be able to be fully open with them if you indeed want to.