I believe he or she is saying that demi is under the larger umbrellas of straight, gay, and bisexual.
Kallen, I suggest that you gather your thoughts on this matter, since it is obviously personal for you, and make a thread concerning the types of romance you would like to see in a future DA game. I personally am not knowledgeable with these specific types of sexualities like demi and ambiguous, etc. Since you frequently post on these boards and are passionate about this issue, I think you should be the one to start a thread. I'm sure there are others who would welcome the topic as well.
Except demisexuality is not. It is between sexual and asexual.
Trust me, I want to. If anyone has any pointers on making a solid argument for an OP, I'd love to hear them.
It wouldn't be a stretch to say that Leliana was demisexual, Alistair, Sebastian, Sten, Shayle, Morrigan. Almost any of the characters. It takes most of the game for them to fall in love with you, and some don't. Leli was tough to romance if your played a female character.
edit: Also, players can not read any sexuality into a character. Characters state their given preference, men, women, both. WE can choose not to believe them, but they will act no other way in the game.
Um, none of these characters are. You can romance any of the LIs before you finish the first main quest after Lothering, and the other's aren't LIs and thus we don't get the sexuality context for them.
Leliana hits it off with you almost immediately.
Alistair is attracted to women by their appearance before building an emotional bond.
Sebastian was a playboy before he took his vows, including one of chastity.
Sten is hard to tell since those of the Qun only have sex for reproduction purposes.
Shale is a golem, so her body has no sex drive. That makes asexual if anything.
Morrigan doesn't want a relationship, she wants sex for the sex. If you get too close, she pushes you away.
As for applying sexuality to characters, I was referring to characters who don't tell you what they are. Those characters are blank slates to the player, so the player can impose whatever sexuality they think fits. Someone could argue that Sten for example is a homosexual, and there is no evidence to oppose them.