Putting Darion in Tirion's place.
:Darion and the Alliance forces confront Arthas, atop Ice Crown Citadel
Darion: Arthas! I have broken free of your control and now I will destroy you!
Arthas: *Laughs* You think you have that kind of power? You have always been and will always be a pawn of the Lich King.
:Arthas takes control on Darion.
Arthas: Now sit and watch as I create the greatest army the Scourge has seen from the force you hand picked!
(Thoughtout the encounter Darion would be battling the Lich King's control.)
Darion: What have I done...
Darion: NO, NO! I did not want this!
(At the end of the encounter, when Arthas is weakened and preparing to destroy the raid with Apocalypse.)
Darion: Father! Give me the strength I need! I must help them!
Alexandros whispers: Darion, it is your time.
:Darion breaks free of Lich King's control and tackles him. Frostmourne is dropped in the struggle before they both fall from the top of the Frozen Throne.
:At the bottom of the Citadel. Arthas is dead from the fall, his helmet fallen and now infront of a barely moving Darion.
Alexandros whispers: Darion... Darion! There is still much left for you to do. Without their master the Scourge will run rampant and destroy the world. Only you have the strength to do what must be done.
: Darion puts on the helmet. As he rises his eyes blaze red with his new power. He turns and walks into the Citadel.
-WotLK End Credits-
Followed by a quest chain to honor Bolvar, who died. And lock Frostmourne away as it could not be destroyed.