There was an interesting discussion in another thread and I thought I would bring the topic to General as I always enjoy a good Paarth discussion. In the other thread it was concluded by those involved that Paarth was a very grey character. Personally, I like Paarth and I understand why people would want to keep him around but in realistic terms, it's hard to justify keeping him alive aside from the personal relationship developed between him and the Dragonborn. But the way I look at it, it's almost like if your buddy got bit by a zombie. Yea, it sucks that you have to kill him, but you know that the consequences for letting him live could be catastrophic. What to do?
I let him live, for two reasons.
1. IMO, there is a major difference between someone who "flips" when there's nothing to lose, and someone who does so when they stand to lose everything. Whether he realized Alduin was going too far, or was actually persuaded by Kyne to help man and mer, he did so at a time when it was not advantageous to do so. At least that's how I see it.
2. If there is one thing I absolutely cannot stand, it's an ultimatum. More often than not, I will do precisely the opposite of what someone demands of me, just because they demanded it. It's hard to play the quest with Delphine and not feel like she see the dragonborn as a tool to be wielded by her, in the pursuit of the Blades' mission. If she wants Paarthurnax dead so badly, I certainly won't prevent her from going to the throat and trying him on for size, but I'll be Talos damned if she's going to force my hand.