Even though N’Zoth has been defeated at the time of this dialogue, Sylvanas is still on the run and seeking to master death.
Jaina: The Old God has been vanquished. The Alliance and Horde have ended hostilities.
Jaina: This should be a day of celebration, Anduin. Yet you wear your troubles like a crown.
Anduin: I’m so glad that after all you endured, you have found peace within your heart, Jaina. I can’t say the same about myself, though. Not yet.
Anduin: Sylvanas is out there somewhere. Until she’s brought to justice, I don’t think Tyrande or Genn will truly consider the war to be over.
Jaina: The Kul Tiran fleet is scouring the seas, and Shaw has spies searching every dark corner of Azeroth. She can’t hide for long.
Anduin: I don’t believe she will. Which is exactly what concerns me.
Anduin: I saw you speaking with a messenger from Kul Tiras, Jaina. Is everything alright?
Jaina: Nothing to worry about. It was a letter from a certain eager cadet asking to see Stormwind… and to learn more about her father.
Anduin: Taelia. Please tell her that this isn’t a good time for visitors.
Jaina: She deserves to hear the truth, Anduin. From you.
Anduin: Tirion Fordring himself made us swear that we would keep the secret of Bolvar’s fate. You made that vow just as I did.
Jaina: I remember your father once telling me that the hardest thing about a promise isn’t keeping it, but knowing when it’s right to break it.
Anduin: Bolvar was a noble man. To know that he sits frozen upon that accursed throne, devoting his very life to keeping the monsters at bay…
Anduin: It breaks my heart. I can’t bear to see it break Taelia’s, too.
Jaina: The decision is yours, Anduin. But if she learns that the truth was kept from her, it will hurt her all the more.
This conversation hearkens back to the dialogue played after from the start of Battle for Azeroth:
Katherine Proudmoore says: King Wrynn, there is someone you should meet.
Katherine Proudmoore says: Along with your champion, she was instrumental in saving our kingdom… and my life.
Taelia says: It is an honor to meet you, King Wrynn. I am Taelia.
Taelia says: Taelia Fordragon.
Anduin Wrynn says: Fordragon?!
Katherine Proudmoore says: Daughter of Bolvar. Fostered under our protection since the third war.
Anduin Wrynn says: Taelia… please, rise. The honor is mine.
Taelia says: Did you know my father?
Anduin Wrynn says: Highlord Bolvar was a great man. A true hero to the Alliance–and to me.
Anduin Wrynn says: I remember now… he used to write you letters. He had a nickname for you…
Taelia says: “My shining star.”
Taelia says: The letters stopped coming. I… I have so many questions.
Anduin Wrynn says: Taelia, when time permits, you must come to Stormwind as my guest. I have many stories to share about your father.
We learn about Taelia being Bolvar’s daughter by the words of Cyrus Crestfall, the Harbormaster of Boralus, during the Alliance Introduction Scenario. Taelia was sent to Kul Tiras by Fordragon himself after the Third War, and Daelin Proudmoore handpicked Cyrus, then one of his most trustworthy knights, to raise Taelia as his own:
When Daelin asked me to leave his guard and raise this child of the Eastern Kingdoms, I struggled to understand why.
Why thrust this burden on me? Why deny me the honor of fighting by his side? I thought maybe I had done something to lose his faith.
Over the years, I have come to realize that the opposite was true. He wanted Taelia to grow up strong of arm and noble of heart - and he had faith that I could make that happen.
Taelia is also aware of her lineage, but she, like all Azeroth denizens, is unaware that Bolvar Fordragon “lives on” as the new Lich King, thinking he died during the attack on Icecrown Citadel. This is shown on the quest:
These days Cyrus is the Harbormaster, but he used to be one of Daelin Proudmoore’s most trusted knights! I lost my mother when the Scourge hit Lordaeron. My father sent me here to be raised away from the war. I don’t know much about him… just that he was a Stormwind knight who gave his life fighting the Lich King. Daelin hand-picked Cyrus to raise me and forced him to take a desk job. It’s the only reason he wasn’t at Theramore. He’s probably checking in that other Alliance ship. Let’s go!