I completely agree with the Original Poster.
Since I've start playing Dragon Age series, all my crushes as a gay male, have been for the Knights in Shining Armor (Alistair on the Top, followed shortly by Cullen (DA:I one, and DA:O one) and finally but not least other Knights).
So I am giving my full support for a Knight who is mainly a gay (male/female), but please don't give them the twin appearance (Just feels wrong)... I've always wanted to find a gay Knight in Bioware games, specifically Dragon Age, because they are my top favorite series.
I agree on the moral code which the Knights follow, loyal, determined, quite bold, protective over the main character... because this is how most people imagine their Knight here. May be having a bit dark side inside of him, which comes up at certain point of the game (preferably at the middle of the main story) so we can add more ingredients to the character and much more in depth personality. A story which will step in properly with the character background/history, including the seed of darkness which hides deep inside of him. And as the game progress actually the player himself have to make the choice, should he persuade his Knight to become a good noble one, or a Dark twisted guy who will still protect him, because let's be realistic... there is a lot of people here who enjoy the dark side of characters and loved to reach it. It's almost the top desired and successful way to make a player happy. Giving him the choice, to either turn his companion completely dark sided or light sided... as it was proven multiple times in your MMORPG SW:TOR.
I enjoy working on characters with deep, complex personalities which step in with their past... So those are my views for the Knight character. I am really hopping that we will see one in the next Dragon Age game.