So people here think Cullen will be a red templar??
I think.... I don't know.
It's a big step to even take regular lyrium, isn't it? Knowing it's addictive, knowing it'll eventually impair you in a huge way. Knowing deep down that it can be used against you as a method of control...
And you take it, why? Because it will make your abilities stronger? Because your religious and professional leaders tell you to?
The same could technically all be said of red lyrium. :/
The only reason Cullen would have to mistrust it is the Meredith thing, and even then he may not have made that connection or could be talked into believing she mis-used her power and got her comeuppance for it.
So I really don't know. It depends on how much Cullen knows about it and who *sells* the idea to him and how. :/ We think of red lyrium as "bad" when really it's just super dangerous. And you could say the same about regular lyrium, which he's already been taking (under Dr. Justinia's orders) for years. *shrug*