I have a 10 and 12 year old. The 10 year old is autistic and the 12 year olds is in full on teen strop mode. I've noticed that they are horrible to me but not so much to their dad. I've been unpicking this.
When he is here (he works away a lot), I try to keep the peace. Tread carefully. Keep everyone happy. But I think when he's away I go the other way and nag and moan (probably because I can't cope with the kids on my own and because he's not here to hear it). They also play up because he's not here and he's the strict one. It's a spiral of negativity!