Barnabas's existence is getting very complicated. David's a threat. Maggie's a threat. Sarah's a threat. Julia and Willie may not be threats, but they keep irritating him when they ought to know that it's their God-given role to support him and fawn on him. It must be wonderful to be so unshakably certain that the world revolves around you, but it has its price.
David turns out to be a little smarter than Burke: at this point he knows better than to run around telling anybody and everybody he meets that Barnabas is bad. And Burke now knows better than to push the subject of Barnabas with Vicky. If I were Vicky, I'd have serious doubts about marrying somebody knowing that there was already one important forbidden subject. But she's young, and in love, so what can you do?
When Julia walked out the door of Collinwood, with that backward look at Burke, I had a strong feeling that as soon as the door closed behind her, she was going to rush to find a phone booth and change into her SuperJulia outfit.