The following discussion contains spoilers for Tamora Pierce's Emelan books, specifically Cold Fire and The Will of the Empress.
Before we dive in, a couple of key terms for you: bisexuality is romantic or sexual attraction to more than one gender. Bisexual erasure is the behavior of downplaying, ignoring, or denying bisexuality. A common form of bisexual erasure is to claim that a bisexual person is "straight" when dating someone of a different gender, and "gay" when dating someone of the same gender.
I also want to point out an important distinction between fictional characters and real people, which is that fictional characters aren't real. They are constructed; who they are and what they do are choices made by a creator somewhere. There are inherent reasons why real people have the orientations they do (even if you believe it's a choice, the ability to make that choice is inherent in the real person), but fictional characters are created subjectively.
Last thing: before I start talking about Tamora Pierce, I think it prudent to remind everyone that I love her books. I really do; they have been helpful and inspiring to me in every phase of my life since I first discovered them. But as I mentioned in Critical Love, loving something does not make it perfect, and the bisexual erasure in the Emelan books stings all the more for coming from a source I trust.
So. On to the discussion!
In Cold Fire, Daja is shown several times to be romantically interested in men.
Usually [Daja] liked to be big and strong: it helped her to handle iron, brass, and bronze. Still, now and then she wanted a little elegance, like the day she found that most boys preferred smaller, more delicate girls, or the day Teraud had shown her iron worked like lace. (p.99-100)
When Daja thought of the healer-mage student she'd fallen for two years ago, she felt her cheeks warm. She had mooned over the fellow for months. (p. 105-106)
In The Will of the Empress, Daja falls in love with a woman and has sexual relations with her.
[On finding Daja and Rizu half-naked in a bedroom] Briar raised his eyebrows at Rizu, then looked at Daja, who scratched at the floor with a bare toe. "Well, that explains more than it doesn't," Briar remarked. He told himself, Now I know why I was sure Rizu was never interested in me, or any man. "Daja, why didn't you say you're a nisamohi?" he asked, using the Tradertalk word for a woman for who loved other women. "What with Lark and Rosethorn, did you think we cared?"
"I didn't know that I was a nisamohi," Daja whispered, still not looking at him. She shrugged. "I've been too busy, and there was never anyone..." She looked back at Rizu, who smiled at her with a beautiful light in her eyes. (p. 359)
Nisamohi is defined in the book's glossary with the single word "lesbian".
So, despite showing in a previous book that Daja was interested both in a specific man and in men in general, she is now labeled a lesbian. Her reason for not knowing she was a lesbian is that she was never interested in "anyone", despite being shown explicitly to have had a crush on a male student that lasted for several months.
Would this scene have lost anything if Daja was bisexual? There was never any indication previously that Daja was not interested in women; she could still have fallen in love with Rizu without disregarding her past romantic history. This is bisexual erasure because as soon as Daja shows interest in women she becomes a lesbian, disregarding her previous attractions to men.
I also find it telling that there is no word in the glossary for "straight", nor do the characters ever think of anyone as being straight. Straightness is the unmarked, default category. It doesn't get its own word because it's considered normal. So Daja being attracted to men isn't really part of an identity - it's "normal". But Daja being attracted to women is an identity - it's "different". This makes it easier to erase Daja's sexuality, because the focus is on what Daja makes different.
This interview with Tamora Pierce shows that she realizes her readers take representation seriously and she believes it's important for her to offer representation:
People started coming up to me at my appearances and saying to me, “When I read that, I realized you were all right with people being gay, and I just wanted to tell you that really meant something to me,” and some of them would actually start crying. And I’m there [thinking], “Of course I don’t care if you’re gay or not!”
I realized if they take that much comfort from that teeny tiny line, then I owe it to them to try, whether I think that I’ll fall on my butt or not. I owe them better than one line. And that’s when I began to try and stretch a little — not try and write the gay experience, but have people there who [are gay].Which opens up the question of why she doesn't believe her bi readers deserve the same representation her gay readers do.
And let me be clear, I think it's wonderful that Tamora Pierce has multiple gay characters in multiple books. She is far ahead of the curve in that respect. I just find it very sad, and hurtful to me as a bisexual woman, that the author shows that two women cannot love each other without erasing any inclination towards other genders. That she portrays Daja as unable to love Rizu without claiming her attraction to the healer-mage student never happened.
This is not the only instance of biphobia in Tamora Pierce's books, either. Her only character identified as bisexual, Rosethorn, is also polyamorous. While there's nothing wrong with being both bisexual and polyamorous, they are not the same thing. It is a common stereotype about bisexuals to claim that all of us are polyamorous, and having the only bisexual character be polyamorous as well reinforces this stereotype. Polyamory is also a trait of the villain in The Will of the Empress, explicitly identified in-text as "greedy". So it can reasonably be assumed that polyamory is not regarded positively in the Emelan books, making it an even larger problem to link bisexuality and polyamory.
There are also some unfortunate implications in the structure of the Emelan series. In The Circle of Magic and The Circle Opens quartets, the four viewpoint characters are Sandy, Tris, Briar, and Daja. In The Circle Reforged quartet, the four viewpoint characters are Sandy, Tris, Briar, and Evvy. As soon as Daja is revealed to be a lesbian, she loses the narrative point of view and is relegated to the sidelines, to be replaced by a younger model. The implication is that the circle of magic is reforging without the lesbian in it.
Was this sidelining of the only queer main character intentional? Probably not, although this interview with Tamora Pierce in which she continually refers to her viewpoint characters as straight and her side characters as gay:
I’m not writing about being gay; I’m writing about people whose friends live their own sexual lives. [...] I’m also sticking fairly close to the main characters’ stories, which doesn’t leave me a lot of time/room to go into the private lives of those around them.
does open up the question of whether Tamora Pierce believes queer characters can be main characters in her books.
More importantly, though, does the author's intent matter? For me personally, as a queer fan who's been reading her books for a decade, the answer is no. It doesn't matter to me what Tamora Pierce intended, because what she actually did was offer me my first real chance to read a viewpoint heroine who was queer like me (if not exactly like me, then at least still queer) and then rip it away, replacing Daja with Evvy. That hurts me, whether she intended it to or not.
Now real people often do struggle with their identities. Gay people may go through periods of time (especially as teenagers) when they believe themselves to be straight, bi people may go through times believing themselves to be gay, and straight people may question their own orientations as well. There is also such a thing as fluid sexuality, in which peoples' attractions change over time. So this is not to say that a fictional character absolutely cannot have different identities at different times. But we didn't see Daja considering her attractions and questioning her identity. We saw a flat switch, "straight" instantly into "gay".
And when what's been portrayed as true love or true affection is suddenly completely wrong, with no discussion or consideration of the possibility of bisexuality, and especially in a series that has run for 11 years and 10 books like Emelan, then it doesn't ring as an authentic exploration of sexuality. Instead it becomes a cheap "let's throw in a token gay character, whether it makes sense for this person or not". The implication is that there is only gay and straight, and it doesn't matter what the character was before.
This phenomenon is also insulting to real gay people, because it implies that gayness is something that can be tacked onto a previously straight person as an afterthought. When characters are originally shown to be interested in a different gender, and then suddenly and inexplicably shown to be exclusively interested in the same gender, it's obvious that the creators think of sexuality as unimportant. It's tokenizing, because it shows heterosexuality as default and homosexuality as something extra that can be appended to anyone.
And again, we are discussing fictional characters, whose lives and identities are created. Daja didn't "really" go from crushing on men to claiming she'd never been attracted to anyone; that was the author writing her inconsistently. This was a choice the storyteller made, not the characters. There's no reason the author couldn't have chosen differently.
Bisexual erasure isn't just inaccurate. It also hurts real people. It shows bisexual people that we're not worth portraying in fiction and that our identities aren't real. It shows non-bisexual people that bisexuals are "really" gay or straight people confused about who we are and that we "really" all conform to stereotypes. As much as I love Tamora Pierce's Emelan books, every time I read them I'm reminded that people like me are erased in this universe - that the author took Daja's attraction to men away before letting her be attracted to women, and that Daja losing the spotlight happened simultaneously with her coming out of the closet. And that hurts.