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?
That's a difficult task indeed!But It's a good question nevertheless so I'll try to answer it.
Let's see,I would probably present him again as an authority figure maybe of the few templars that decided to stay loyal to the divine,someone who commands respect and have people willing to follow him.It would be an interesting journey from a recruit to a knight-captain(also high ranked figure) and finally a leader.Yet someone who doesn't exactly thrive in power,for him it would be more like an unpleasant task that his honour and dedication to his duty,will prevent him from not completing.To be honest I'd probably give him the role of an ally rather than a subordinate.
I wouldn't change much,except from perhaps making him more confident about himself and his ideals,slightly suspicious and cautious,you'd have to work hard to earn his trust,mainly due to his past experiences.Also someone who doesn't hesitate to express his doubts on his ally's methods and motives,as soon as you cross the line he'll be the first one to confront you about it,again due to past experiences and most importantly more active,ready to take matters into his own hands if he has to,in a way a leader would.
Perhaps,I'd also make him more open minded about some subjects,capable of seeing the grey in what he previously considered a black&white situation.
As far the inquisitor is concerned he'll be initially wary of them.Whether he'll start to warm up or become even more hostile will depend on the inquisitor's actions and morality.Cullen despite being viewed as a morally complicated figure by some,makes it obvious that he strives to stay on the righteous side,so I assume an inquisitor who acts righteously and justly,is more likely to win his trust.The same applies for the companions,although some prejudices will be difficult to overcome,I would make him capable of reconsidering them and finally overcoming them,but there would definitely be a certain line he'd refuse to cross,as far as his views are concerned.One good example is blood magic.
He'd probably have an important impact on the story and not because I like him as a character...Ok maybe a little,but the main reason would certainly be his experiences so far.He is one of the few characters that not only has seen the worst of both worlds(mages vs templars),he also played an active role in the beginning of this feud along with Hawke and company.But unlike the rest,his position as a templar makes him far more involved in the events.
Secondly it's the importance that the red lyrium and the red templars,appear to have in the events of inquisition.His input as a templar who witnessed the effects of red lyrium first hand,would certainly be valuable for the main character and the rest of his party,who are now required to fight them.
Not to mention that I'd probably have him do some research about the red templars, since the subject concerns him.
Yes,I would,his specialization tree would probably be that of a templar mixed with another specialization for warriors that is not focused on negating magic,he won't always fight mages as a follower.