"At the moment, because it's always subject to change, I identify as kind of more non-binary, but male presenting."
Maxine Fleming, Shortland Street producer, said around a dozen actors auditioned for the role.
"It's a tricky issue, it's a political issue in some ways, but we're just trying to tell the story as authentically as possible - obviously starting with the decision to cast a transgender actor in the role."
She said the storyline was "timely".
"Other shows are doing this - Transparent and Orange is the New Black. It just seemed very much at the forefront of the zeitgeist . . . I think we have always tried to mirror diversity. It's not an issues based show, but we do explore issues through character."
In a 2012 survey of New Zealand high school students, four out of every 100 reported they were either transgender or not sure about their gender. Around 40% of those had significant depressive symptoms.
"We are going out of our way to treat this as a very positive story," said Fleming. "There are challenges and I know that transgender teenagers have difficulties, but we're not going down a dark path with Blue's story."
Shortland Street - the 7pm medical soap that celebrates its 25th birthday next year - has featured transgender guest characters in the past, but "this is the first time we've featured a transgender character playing a transgender actor in a long-running storyline".
Fleming said the year-long signing meant writers could create a three-dimensional character.
"We can explore more realistically and fully the journey the character goes on. You can't do that if you've only got someone in for two weeks. We can do drama with them, we can do comedy - it doesn't have to be about the fact that Blue is transgender."
Keddy, most recently an Elam School of Fine Arts student, has no acting experience and, at his audition, had to admit he'd never watched Shortland Street.
"We talked to Tash extensively to ensure he was up to the challenge of this and was robust enough to deal with the attention it was going to bring, and also had the right support in his life," said Fleming. "We were convinced he was the right person for the role."
South Pacific Pictures, the production company behind the show, had brought in a consultant from the transgender community, Cole Meyers, to assist with the introduction of Keddy's character.
Meyers (who will also feature on screen later this year) said the casting was "huge".
"It is a big deal . . . we're at a point where we have so few trans narratives, and every single one has a huge amount of power."
Meyers said depictions of trans people in popular media could either empower young people who were questioning their gender, or "frighten them so much they stay inauthentic to themselves. They stay hidden, and in pain, and they don't talk about it, or they only expect that their future is bleak or that they can expect violence and social exclusion".
Meyers said he anticipated a positive reaction to the casting.
"The fact that Shortland Street is committed to this long, ongoing characterisation of a young trans person and is also not just focussing on the physical, transitional element, but seeing them as a whole person - interesting, multi-dimensional, multi-talented, multi-hobbied, just like everyone else - that has a huge effect."
• Read the full Canvas feature here.
