At work the other day I was sat in my office on a teams meeting when a coworker has banged on my window aggressively and pulled faces, thinking it was funny. I've finished the meeting and have shouted at him not to do that again as it was unprofessional. He's then apologised and started to joke around. Cut a long story short, he's had time to think about it overnight and has cone to my office yesterday, told me that I need to listen to him and that I'm the one who is unprofessional for what I did to him. The air turned slightly blue to put it mildly and then he's left only to return seconds later to ask for something work related which I said for him to speak to a manager not me. He has been berating me for months and I've always stood up for myself but I think it's getting out of hand now. Should I put a greiviance in or just ignore him?