A human mage, Anders is the face of the whole anti-templar movement. Also a constant character throughout the series, he is a main companion and works well in balance with Morrigan and Varric.
It's best to keep him away from the Templars, blood mages and never, under any circumstances, let him see the player striking deals with demons. Strong opinionated and on the run his whole life, Anders can quickly turn on the player and even leave the party.
It would be interesting to make a game in which Anders and Cullen are in antithesis and fight for what they believe in. Anders journey and time in the Circle of Magi is also something that could and should be explored more.