Patch 5.1: Wrathion Quest Line
The last thing we heard from Wrathion were his instructions to await the fleet's arrival in Patch 5.1. After meeting the scout, and clearing the way, the fleet will arrive.
You can then visit Wrathion again, who wants to learn more about Varian. You must then prove that your faction should win the war by earning Revered with him, which is done by killing forces of the opposing faction in Krasarang Wilds. There are some side quests along the way, such as winning 10 battlegrounds or taking a group to kill a general.
After you are revered, Wrathion will call you back to tell you what he has learned about Varian. This is seemingly where the quest line stops for now. It may be incomplete, as the Horde side of the quest line is not even added yet.
That isn't all Wrathion is doing in this patch however. Warlocks can obtain a Sealed Tome of the Lost Legion that is sealed. After binding it to you and consulting with one of your demons, you can take it to a Warlock trainer to find out more about it.
You then visit Wrathion, who asks you to read Legacy of the Masters (Part 1). You are then sent to General Nazgrim / Admiral Taylor to let him know that you are going to try and recruit The Council of the Black Harvest to aid in the fight against the Alliance / Horde.
Next, you infiltrate the opposite faction's base to obtain the second part of Legacy of the Masters. You retrieve Jubeka's Journal from them, which has clues as to the location of four Soulstone fragments that contain memories. Once you have collected them all, you combine them and follow the source of the power to the Black Temple.
You then follow Kanrethad and Jubeka's trail to the top of the Black Temple. While on your way there, Akama will make another appearance in the area where you fought Bloodboil. He is under attack by forces you unleashed in the Reliquary of Souls, so you assist him and then make your way to the summit.
Once there, something happens that creates The Eye of the Storm. You then return to Wrathion to try and find out what it is. He doesn't know anything about it, but is willing to ask his agents. They are busy with the Horde and Alliance war, so you will have to wait until Patch 5.2 to find out what happens next!