Amara Tanith

The reason why can be anything... maybe he was holding Hawke's or Anders's staff while a templar patrol was walking by, and they decided to smite first, ask questions later. Feel free to hand-wave it. In any case, no one listens to him when he says he's not a mage and that they should contact Elthina to confirm his story. He gets the Alrik treatment - abuse, torture, rape, the worst that can happen to a mage other than Tranquility. Or he gets the rite, except obviously it doesn't work, so the templars try harder.

By the time he is rescued, his opinion on templars & the Chantry has changed quite a bit. OR he doesn't get rescued - instead, someone finally realizes that he's not a mage, they release him, but offer no apologies or explanations, since they believe it's better to be safe than sorry when it comes to potential apostates, he should understand as a Chantry man.
Healing & comfort from Hawke & co would be very welcome, especially from Anders! (Anders/Sebastian is my guilty pleasure ship...)

Squicks are bathroom stuff, character bashing of Sebastian or Anders (feel free to go wild on Elthina/Meredith/templars though), major character death.

http://dragonage-kink.livejournal.com/15195.html?thread=61059931#t61059931