Varys is my favourite character by far...just something about him so I was happy to see him return but then sad to see Kevan die like that..he might have restored KL back to its old state before war broke out.
That is exactly why Varys appeared... That was the one thing he was trying to prevent... Kevan reconciled their differences with the Tyrells, and peace and prosperity seemed to be around the corner... He could not allow that, so killed both Pycelle and Kevan... Cersei would think it was the Tyrells, and we will have another war on our hands pretty soon... It was Varys intention to have the kingdom in chaos when Targaeryans arrive, so it would be easier for them to take the rest out one by one, while exausted by wars. Kevan had to go, he was the perfect regent at the moment, it seemed.