[sblock=GM Thoughts]Frankly, I see no problem with Ariel the NPC and Fae'shiel. That is all in DC's head.
I think that DC forgets that the relationship between Ariel run as a player leading another adventuring party where his character joined as newcomer was completely different than when I NPCd the same character later on. The beginning butting heads was mostly because Veniarus was being a pompous ass, IIRC.
The main difference is that Ariel as a player character was run by a person that drives a game, posting often and moving things forward and is heavily involved in talking with NPCs and group decisions. Conflict was often inevitable since Ariel was a zealous and had little sense of humor.
But I do not want to have Ariel making decisions for you and providing answers to plot issues. That would be like playing with myself.
I am a very experienced DM, used to running NPCs in a party like an equal and still letting the players take the spot-light and make the critical decisions. The fact is that I have 7 games where I am doing that as DM and half the players are unaware.
EnWorld just happens to be the one Forum I an not doing it at the moment. But, I don't recall anyone complaining when I used my characters as NPCs before. Mfloyd3's opinion of having Ariel with him during the two encounters would be your best impression of how it would be like. And Veniarus was in one of those same encounters too.
The only time I would see Ariel causing conflict would be if you all decided something that really against her LG morals. But her vote still doesn't count in the player consensus. It would all be role-playing only. I might use her as a tool to give you advice to keep from TPKing yourselves, but only if it is reasonably something she would know or believe. She might have opinions too, but if you meta-game that might be dangerous.
My idea would be to tie Ariel's experience points to be the same as Iago's so your cleric will not be behind in levels. I will retool her away from being focused on ranged and get her Heavy Armor Proficiency to make her more a front line character instead to help resolve the issue of not having a tank.[/sblock]