- “These robes are gonna get their lesson.”
In Act 1 Karras is involved in the quest Act of Mercy. After getting a letter from Ser Thrask, Hawke will travel to the Wounded Coast and will end up outside a large cave. Thrask will tell Hawke that a group of apostates who've fled custody after the Circle of Magi at Starkhaven burned down, are hiding in the cave. He will also tell that Karras is on his way, and he will most likely kill the mages. When Hawke enters the cave, the apostate leader, Decimus, will attack him/her on sight with a few of his followers. After he is killed, the rest of the mages will ask Hawke to help them escape. As Hawke exits the cave, Karras will arrive leading a group of templars.
- convince the mages to go with Karras and Thrask to the Circle.
- lie to Karras that the apostates are dead and that Decimus has fled to the Wounded Coast through the caves. This requires either a sarcastic Hawke or having Varric in the party. Varric will also feed Karras a line that Hawke is either Ser Hawke from the Ferelden Templar Order (warrior or rogue) or Enchanter Hawke from the Ferelden Circle (mage).
- kill Karras and the templars who came with him. Thrask will help Hawke.
If Karras is killed:
Several years later a Templar Knight-Lieutenant suspecting the involvement of both Thrask and Hawke in Karras' death will lure Hawke into an ambush in an attempt to avenge his death.
If Karras is not killed:
In Act 1 Alain in the Gallows courtyard will tell Hawke that Karras promised to make him Tranquil if Alain told anyone he has been in Alain's chambers.
In Act 2 Karras stands in the Gallows courtyard and, when clicked, will predict that, "As soon as the Qunari are gone, the mages will make their move, mark my words." If Hawke lied to help the mages escape, Karras will say "You lied about the mages, but we caught them anyways."In Act 3 Hawke can talk to Karras in the Gallows courtyard. He will tell Hawke that Meredith "has sent to Val Royeaux for the Right of Annulment" which can give you the Codex entry: The Right of Annulment.
- Ser Karras wields the Edge of Song and Glory longsword, which can be looted if you kill him.