He would make a pretty poor raid boss based solely on the fact he still uses a cute dragon whelp model :P
I dunno, the only way i can see it is that kinda like in Watchmen, you need a worldwide threat to stop infighting. But after living through 2 of them in the last 2 expansions (and vanilla if you count might of kalimdor), it's pretty clear once we unite against any worldy threat that we then go back to killing each other.
This quest which was added in the patch that added dragon soul
To Catch a Thief
Which takes place after The Egg Lives On added in cata
Which is the end of a long chain where you purify a black dragon egg. HIS egg!
Seriously please read up on the existing lore of Wrathion, a good place to start would be Wowpedia's Wrathion article
The real problem is the way blizzard wrote the line, it should have been "In your years but not in dragon years."
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he hatched in ravenholt manor during the rogue legendary dagger quests
well no but the first quest in the chain "Proving Your Worth" is from the red dragons and the state of urgency of the egg was recently stolen, and the red dragons still think he is an egg up until you find him and you do see the cracked empty shell right behind wrathion when he says
so he hatched some point between "Proving Your Worth" and the end of "To Catch a Thief"Wrathion says: That's right, mortal. The prize you seek no longer sleeps within a shell. Here I am: in the flesh.
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nope hes a whelp hes a whelp at the end of the rogue chain and in MoP
Wrathion cannot be a "filler raid" boss. A filler raid would have a random non-lore significant character.