Studies suggest that most people who transition to another gender do not have second thoughts. But after two trans men met and fell in love, their personal gender journeys took an unexpected turn, to a destination neither had foreseen.
"I always felt we have a very special history. We have special bodies, and a special connection based on the physical experience we had."
Ellie is 21 and Belgian. Her German partner, Nele, is 24. Both took testosterone to become more masculine, and they had their breasts removed in double mastectomy surgery. Now they have detransitioned, and live again as female - the gender they were assigned at birth.
"I'm very happy I didn't have a hysterectomy," reflects Nele. "It means I can stop taking hormones, and my body will return to looking feminine."
Last year, they both made the decision to end their use of testosterone and start using the female pronouns "she" and "her" again. Slowly their own natural oestrogen has begun to re-feminise their bodies.
"I'm very excited to see the changes," says Ellie.
Their faces have softened, their bodies become curvier. But years of taking testosterone has had one profound, irreversible effect.
"My voice will never come back," says Nele. "I used to love singing and I can't sing any more - like my voice is just very monotone, it works very differently. When I call someone on the phone, I get gendered as male."
The stories of these two young people are complex.
They may not be typical of people who have transitioned to another gender. And they are not a judgement on the decisions of other trans people, be they trans men, trans women or non-binary.
Ellie does not remember being uncomfortable as a girl when she was a child. But that changed as she became adolescent.
"I realised I was doing a lot of boy things, and some people weren't fine with that - especially other kids. I remember being called things like 'hermaphrodite'."
Tall and athletic, Ellie's love of basketball was identified as, "a boy thing" too. At 14, she realised she was attracted to other girls, and later came out to her parents.
"I was dating girls and happy about it," she says.
Then Ellie told her sister she was a lesbian.
"My sister told me she was proud of the woman I was becoming. And somehow that rang a bell for me. And I remember thinking, 'Oh, so I'm a woman now? I don't feel comfortable with that.' It wasn't that I wanted to be a boy - I just didn't want to be a woman. I wanted to be neutral and do whatever I wanted."
At 15, Ellie believed becoming a woman might limit her choices in life. For Nele too, growing up female was not fun.
"It started with puberty, when I was around nine years old - with getting breasts before I even realised what it means to have them. My mother forbade me from going outside bare-chested. We had a lot of fights because I was like, 'Why can my brother go out bare-chested?' Obviously, my mother wanted to protect me, but I couldn't understand at the time."
As Nele matured, there were also lecherous men to contend with.
"I experienced a lot of catcalling. There was a street next to mine, and I couldn't go down there without a man hitting on me. I'm slowly realising now that I internalised all of that - that I was perceived in society as something sexy, something men desire, but not a personality."
With her body developing fast, Nele saw herself as too large. She would later develop an eating disorder.
"Too fat, too wide - the thoughts about needing to lose weight started very early."
Nele was attracted to women, but the thought of coming out as a lesbian was terrifying.
"I really had this image that I would be this disgusting woman, and that my friends wouldn't want to see me anymore because they'd think I might hit on them."
At 19, Nele came out as bisexual - that seemed safer. But the experience of unwanted male attention and the discomfort she felt with her female body stayed with her. Nele fantasised about removing her breasts. Then she learned trans men get mastectomies.
"And I was like, 'Yeah, but I'm not trans.' And then I was like, 'Maybe I could fake being trans?' And then I was doing a lot of research and I realised a lot of those things trans men say are very similar to what I experienced - like 'I always felt uncomfortable with my body, and as a kid I wanted to be a boy.'"
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Listen to Ellie and Nele in The Detransitioners She2He2She on the BBC World Service - click here for transmission times
The distress trans people feel because there is a mismatch between their gender identity and their biological sex is called gender dysphoria. Nele thinks her own dysphoria began around this time.
"I thought, actually, 'I don't have to fake being trans. I am transgender.'"
Nele could see only two options - transition or suicide. She sought help from a transgender support organisation. They sent her to a therapist.
"When I arrived, I was like, 'Yeah, I think I might be trans.' And he directly used male pronouns for me. He said it was so clear I'm transgender - that he's never been as sure with anyone else."
Within three months, Nele was prescribed testosterone.
Ellie too became determined to access male hormones - in her case when she was just 16.
"I watched some YouTube videos of trans guys who take testosterone, and they go from this shy lesbian to a handsome guy who is super-popular. I liked thinking of myself having that possibility - it felt like I should have a male body."
But being so young, she needed parental approval for any medical intervention. The first doctor she visited with her parents said Ellie should wait - she thought that was transphobic and found another medic who was positive about her desire to transition.
"He told my parents that all the effects were reversible - which is the biggest lie. I had done my research, and I knew that this doctor could not be trusted. But I was just so happy that he said that, because then my parents were OK with it."
Ellie's dad, Eric, was worried about the impact testosterone would have on his child's health, but the doctor reassured him.
"We were still in shock from having a girl who wanted to be a boy," he remembers. "And the doctor said hormones would be better for her."
Eric and Ellie's mum felt all at sea in this new world of changing genders.
"I would've liked to have met someone to give me the words and find arguments to make her wait and think about it longer, but there was no-one," he reflects.
At first, testosterone made Ellie feel emotionally numb. Then she felt much better. At 17, she had a double mastectomy. Later, she graduated from high school, and left Belgium to go to university in Germany.
Transitioning to male had not ended Nele's feelings of despair. She was still suicidal, and her eating disorder was manifesting itself in extreme calorie-counting, and an obsession with her diet. Nele began to think testosterone was the only good thing in her life - and she still wanted a mastectomy. But she did not feel she could be totally honest with her gender therapist.
"I was very ashamed of my eating disorder. I mentioned it in the beginning, but I didn't dare talk about it more because of the shame - I think that's normal with eating disorders."
Nele was worried her transgender treatment might be halted if there was any doubt about her mental health.
"It's a very tricky situation in Germany, because the therapist is the one who gives you the prescriptions for hormones and for surgery."
There are few studies exploring the link between eating disorders and gender dysphoria. One review of the UK's Gender Identity Development Service in 2012 showed that 16% of all adolescent referrals in that year had some kind of "eating difficulty". But bear in mind that most referrals are young people assigned female at birth - natal girls, as they are called, who are more vulnerable to eating disorders than their natal male counterparts.
Brian and Daniel have been on a similar journey to Ellie and Nele but from a different starting point. Both were assigned male at birth, transitioned to female, and later detransitioned to become male again.
Some clinicians have suggested that eating disorders develop as a response to gender dysphoria, says Anastassis Spiliadis, a UK-based psychotherapist who treats patients with eating disorders and gender identity issues.
The theory is that if you treat the gender distress, the eating disorder will diminish. This can happen, but it is not what Spiliadis has seen among many of his clients - natal females in their 20s who, like Nele, are detransitioning.
"They thought transitioning to a different gender would alleviate the eating disorder and the dysphoria, but things have been much more complex. They regret the decision to take testosterone and have surgery. But what's really worrying is that some of them still have an eating disorder."
He believes someone who is suffering from anorexia or bulimia may not be equipped to make irreversible health decisions.
"We know that eating disorders affect people at a bio-psychosocial level. Those who are medically and physically, but also cognitively compromised might have a distorted view of themselves or their bodies."
Spiliadis believes good practice in this field should mean screening young people with gender identity issues for eating disorders. And because they are life-threatening, eating disorders should be treated before responding medically or surgically to the distress caused by gender dysphoria.
As a new student and trans man in Germany, Ellie thought her own dysphoria was a thing of the past, and she was getting on with life.
"I was passing as a man - I was passing so well. I got so many comments from people telling me my transition was such a success, because they couldn't tell I was trans."
But an ambivalence about her male identity crept in.
"I started to feel like I had to hide so many aspects of my life, and not talk about my childhood as a girl. I didn't feel comfortable being seen as a cis man, and I started to feel like I didn't fit in anywhere."
Transgender or trans - a person whose gender identity differs from their assigned sex at birth
Cisgender or cis - a person whose gender identity does not differ from their assigned sex at birth
Non-binary - a person who doesn't identify as only male or only female
Pansexual - a person attracted to others regardless of their sex or gender identity
Dating was problematic.
"I wasn't comfortable dating women because I didn't want to be taken for a straight guy. And this discomfort I had with my own body parts… Well, I started to see female bodies as less good-looking, less valuable in a way."
Ellie began to be attracted to men and identified as pansexual.
"I think that came about because of internalised misogyny. But I never really felt any connection with any cis men. Then I thought, maybe dating another trans man would make me feel close to someone and attracted at the same time."
Did it work?
"It totally worked!"
So Ellie went on a dating app and met Nele - who was not especially looking for romance with another trans man.
"But it was definitely a plus when I started texting with Ellie. We share a lot of experiences, and I feel very comfortable around her."
After a first date in Düsseldorf, their relationship moved swiftly. Nele got the go-ahead for a long-desired mastectomy, and Ellie was a great support. The couple moved into a flat together.
And it was around this time that Ellie, a gender studies student, became interested in the culture war between trans activists and radical feminists that often erupts in the social media ether.
She started to question whether she was really transgender. "Or is this just a way I found to go through life?" she wondered.
Ellie and Nele had intense discussions about their own identities.
And there was something else - both were diagnosed with vaginal atrophy, a soreness and dryness commonly found in menopausal women, but also a side-effect of taking testosterone. The remedy was oestrogen cream.
"But it didn't really help," says Nele. "And I thought, 'I'm putting my body full of hormones, when my body can make those on its own.'"
Ellie felt the same way.
"Isn't it worth trying to go natural for a bit, and just see how it goes?" she thought.
That is when they stopped taking testosterone. But the decision to detransition was daunting.
"I was afraid of ending the hormones and going back to my body. I didn't even know my natural body because I transitioned so early," says Ellie.
"The thought of going back was scary, because I transitioned to escape my problems. Detransitioning means facing the things I never managed to overcome," says Nele.
There is little academic research about detransition. The studies that have been done suggest the rate of detransition is very low - one put the proportion of trans people who return to the gender they were assigned at birth at less than 0.5%. But so far, researchers have not taken a large cohort of transitioning people and followed them over a number of years.
"The longitudinal studies just haven't been done," says Dr Catherine Butler, a clinical psychologist at the University of Bath.
"But on social media - for example on Reddit - there's a detransitioning group that has over 9,000 readers. There will be academics like myself who are part of that, but even so, it is a huge number of people."
The lack of academic research in this area has an impact for those re-thinking their gender journeys.
"It means there aren't guidelines or policy that informs how statutory services can support detransitioners. So they've had to self-organise, to establish their own networks," she says.
And that is what Nele and Ellie did. Using Nele's skills as a professional illustrator, they created post-trans.com - an online space where people like them can get in touch and share their experiences.
Both of these young people are conscious of how stories of detransition have been used by transphobic organisations and commentators to invalidate the experience of trans and non-binary people, and attack their hard-fought access to health care. Neither Ellie nor Nele deny the rights of trans people. They do, however, question whether transition is always the right solution.
Now, just months into their detransition, they are adjusting to life as female and lesbian. And so are their friends and family.
"It was hard for her to call us and tell us," says Eric, Ellie's father, who is still getting used to using female pronouns for his once-again daughter.
"It's not black or white for me. I knew from the start when she first transitioned she would never be a man - she never had the idea of having the complete operation. So now it's a new in-between somewhere, but it's always her."
So does his daughter regret her choices - her mastectomy, for example?
"All those physical changes I experienced during my transition helped me develop a closer relationship with my body - they're just part of my journey," says Ellie.
Nele is similarly sanguine.
"Bodies change through ageing and accidents - I don't feel sad my breasts are gone."
Neither plans to have reconstructive surgery. More difficult sometimes is the experience of once again being gendered as female - especially by men on lonely station platforms at night, who might be a threat.
"Because if he perceives me as a man, I wouldn't feel that… But if I'm seen as a woman, maybe I'm in danger and have to watch out," says Nele.
But her experience - from "she" to "he" and back to "she" again - has also had a positive impact, especially on Nele's career.
"I always perceived myself as, 'Well, I'm just a girl who draws - I couldn't be a professional, self-employed illustrator.' And then I transitioned to become a man, and suddenly I was like, 'Oh, I can do those things.' It's something I hear a lot, that trans men feel more confident. I had the same experience. So I will take that and keep it."
Ellie and Nele boarded a gender rollercoaster when they were still teenagers. It has not been an easy ride.
Now they are moving on, looking forward to life - perhaps with the addition of some pet cats.
Ellie and Nele approve of the use of female pronouns to refer to them throughout their lives, including when they were living as trans men.
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