For what it's worth, Alistair, Merrill, and Sebastian all struck me as quintessentially "good", but I'll be damned if they didn't have huge glaring flaws. Like, the size of craters.
You can be someone who strives to do the right thing and still fucks up all the time.
I totally agree. All three of them are 'good' characters and all of them had really giant flaws. So giant that each have dedicated bases of the fandom that dislike the characters.
Keeping on the KISA point, I think a KISA with a flaw is a much more interesting and dynamic character than ones that don't have flaws. Don't get me wrong, I liked Ajantis too. But I find DA KISA's, each of whom is flawed, to be more interesting overall. I'd like to see a gay KISA have some flaws as well. Otherwise, s/he'd come across as a flat stereotype of a character.
To be honest, I don't even mind a character like Blackwall. I know that Thomas Ranier was certainly not a KISA, but "Blackwall" was, even if it was originally as a facade to hide his identity. But the Blackwall that I recruited and fought beside as an ally was very much a KISA in many ways. I thought that his story was a really interesting twist on a KISA archetype.
I also like the idea of a KISA who is dedicated to the other side of the conflict at first and eventually comes around to join the PC. Like the idea of a Ser Cauthrien style character who is bound by honor to serve the antagonist and is a minor antagonist at first.