With Serenity and Johnny.

After Dorian brought the two to the throne room, he ordered everyone including Timothy and Artemis to leave the place, as he claimed to speak with the two privately and with no one witnessing.
After giving a couple of words to Serenity, she too is asked to leave and to head to a room where she will be staying.
Once alone with Johnny, he explains him why he took that decision, since so far he told about it only to Dorian, not intending to make certain private things public.
It was done because their spies came to realize how Chloris was only using Johnathan without him to even realize. The fact he allowed such a thing to happen thus putting his power in the hands of that traitor was unacceptable and made him no longer suitable for that role. And since no one else would be considered trustworthy enough to give "vampires" another chance, the final move was needed.
Johnny is not directly deemed responsible of anything, in fact, Morgan is not angry at him, but he was no longer willing to take risks from uncertain and unstable creatures who could turn dangerous for the citizens.