Dragon Age II: Legacy allows you to choose whomever you want for your party makeup, but there seems to be a few choices that provide more flavor than others.
For example, Varric has a ton of cutscene dialogue (at least early on) and one of the achievements/trophies for the DLC requires Bethany/Carver to be in your party when you complete all the quests.
On the other hand, Merrill doesn't seem to have any cutscene dialogue (again, at least early on), and just acts as a bit player, not even acknowledging a prior relationship.
Do any of the other companions play more of a role in the DLC? Or are the only two important characters per se Varric and Bethany/Carver?