You have been given the difficult task of writing all of Cullen's dialogue.
How would you present this character?
What changes would he make from DA2 to DAI?
How would you make him interact with The Inquisitor and companions?
What impact would he have on the story?
Would you make him a potential party member?
If yes, what would his unique companion combat specialisation tree be?
Ok, I'm really late to this one, but I wanted to answer it anyway:
How would you present this character?
I guess I'd present him very much in the same way that he's been presented so far. Keeping things true to his past story arcs I'd have him at a stage in his life where he 's feeling battle weary because life has been difficult for him ever since DA:O, that being said he'd still be very professional (perhaps too much so initially). Gradually I'd have him begin to warm up and not be quite so stoic 24/7, which is where we'd get to see the man behind the Templar. As for his introduction I think I'd like to have him charge in to save the day as the Inquisitor 'n' co find themselves losing a surprise attack against the Red Templars or something.
What changes would he make from DA2 to DAI?
He'd be at a point in his life where he's realised that any form of power (be it magic or other) can corrupt a person, that it's not just mages who are in danger of going off the deep end and that it really depends on the individual's personality and strength of will as to whether or not power will corrupt them. He's no longer with the Templar Order (as it stands) because he did not agree with severing ties with the Chantry to go rogue. Instead he now has his own militant faction (either formed off his own back, or given to him by the Divine) which he was using to try and combat the Red Templars until the veil breach ripped open, since then he and his little army have been dealing with the demons pouring out of it.
How would you make him interact with the Inquisitor and companions?
When interacting with the Inquisitor, initially he'd be very professional because he's there to do a job, help get this veil breach closed and put an end to the chaos. He's not expecting or even looking for friendship, companionship or love, he's there to do what he's always done: fight and restore order. Regardless, he finds himself attracted to the Inquisitor from the minute they meet, but for the first few interactions/conversations with the protagonist he'd be very much the same as he was in DA2 where it's all very formal and business like, but even during those conversations little glimpses of his personality would shine through (just as it has always done). With encouragement from our protagonist he'd gradually start to open about his past, personal life, likes/dislikes and all the usual stuff we get to talk to companions about, during which he'll start to give away subtle little hints that he's developing feelings for your character (if you've encouraged it). The romance arc would build up from there at a nice steady pace that spans throughout the whole game, along with his story arc.
In regards to how he'd interact with companions it really just depends on what each character's personality is like, so I can't really answer that one just yet.
What impact would he have on the story?
I would like the see a large bulk of his impact be about the red Templars since they were once his brethren. I can only imagine that witnessing them huffing red Lyrium and becoming abominations is bound to have some sort of impact on him mentally and emotionally, not to mention the fact that the majority of the Order also severed ties with the Chantry. In theory the fact that the veil has ripped open and demons are pouring out would also be a critical plot point for him to be involved with, so if I was writing his script he'd at the very least have some important input into getting the thing closed. To be honest, I think the most important thing surrounding Cullen's inclusion should be more about how the story impacts him, how he deals with those experiences and whether he learns and adapts to it, or lets it consume him, much in the same way that all the companions from the previous games have been written.
Would you make him a potential party member?
If I had my way? Absolutely yes! But I think by now it's pretty obvious that he's just an important npc working closely with the Inquisitor (seemingly one of those 3 advisors that the devs have spoken about), which is a shame but I guess we can't really pass judgement on how much involvement he/they'll have or how much interaction we'll actually get with them until we know more.
If yes, what would his unique companion combat specialisation tree be?
Well, first and foremost his baseline talents are part of the Templar specialisation, so he'd get all the usual skills that come with it like smite and cleansing aura etc. I'd also like to see him have talents that involve strength of will and fortitude, along with a skill set that requires a warrior who has trained his mind to stay focused (which would suit him well, considering the amount of head mess he's had to force into the back of his subconscious in order to function and not completely breakdown).
Retour en haut
. Or "Cullen....this tunic matches your eyes. ADORN IT UPON YOUR BODY BECAUSE IM SAVING THE WORLD!!!!" Then it gets a liiiiiitle creepy. But they should totally let us dress up our advisors ANYWAY because if nothing else think of all the great comics that will be made!
as well as some squishy romance 
