Much of what happened to Anna-Louise Bates on the terrible night a careless driver wiped out half of her family remains fragmented.
She remembers pushing her daughter, Elizabeth, three, in the stroller as they walked home from a Christmas party.
Her husband, Stuart, and seven-year-old son, Fraser, were ahead. They were in high spirits, crossing the road while singing: 'I will walk 500 miles' from The Proclaimers' hit I'm Gonna Be.
There was a bang. Screams. Sirens.
Stuart, 43, died at the scene. Fraser, who suffered 'catastrophic injuries', was taken to intensive care at the Royal Glamorgan Hospital in Cardiff.
Anna-Louise fell to her knees when doctors told her he was brain dead. 'You've just taken away my husband. You can't take away my son,' she wept.
She recalls the conversation about organ donation. Paperwork. Kissing her son time and again.
Anna-Louise Bates (left) lost her son Fraser, 7, when a driver hit her family as they walked home. Fraser's heart was transplanted into Roman Pickering (pictured with mother Zoe)
And then, the 'hardest thing ever': leaving Fraser at Bristol Children's Hospital, where his heart was kept beating on life support until an operation to remove his organs the following day.
'I just remember the house being like a revolving door of people, but it was white noise to me,' says Anna-Louise of the trauma six years ago.
'All I did was watch the phone so I'd know when the operation had been completed and my boy was at peace.'
Today, Fraser's heart continues to beat. It was transplanted into a ten-month-old boy, Roman Pickering, within hours of Anna-Louise being told Fraser's operation had been a success.
Now six, Roman is undergoing tests at Great Ormond Street Hospital for a kidney transplant (kidney failure is a common complication from the anti-rejection drugs needed following a heart transplant).
Extraordinarily — as it is extremely rare for a donor's family and the organ's recipient even to know each other, much less meet — Anna-Louise sits with Roman. She hugs him and it's as if he's known her all his life.
Yet this is no bond built up over years. The pair met for the first time last week at London's Rainforest Cafe.
The two mothers were astounded by the uncanny coincidences which link their boys. How on earth can it be explained that they adore the same song, have the same hobbies — and that Fraser's mother sees her son's heart and soul in the eyes of Roman, and he instantly took to her?
'You look into Roman's eyes and you can just see the heart,' says Anna-Louise.
'Yes, he's poorly. Yes, he's got his tracheostomy [a tube inserted into his windpipe to help him breathe during the 100 or so operations he has undergone in his short life], but I didn't see any of that. It was like looking into one of my children's eyes.
'Roman's are big and blue. Fraser had my brown eyes but it's not about what they look like. I really feel now...' she searches for the words.
'You know when people say, 'You can look into someone's eyes and see their soul?' That's how I feel. I see Fraser's heart and soul. It gives me such joy, such peace.'
Extraordinarily — as it is extremely rare for a donor's family and the organ's recipient to know meet — Anna-Louise (pictured with Fraser) met Roman and his mother Zoe last week
Anna-Louise, a former lawyer, is not daft. She knows the heart is a muscle and that Fraser had already 'passed away' when his was removed.
'It freaks me out,' she says. 'But does a heart not define every person? Don't we all talk about our hearts? How they're broken? How they're mended? How our hearts have grown?'
Roman and his twin brother, Hunter, were born to Zoe, 32, in January 2015 when Fraser was a healthy, football-mad six-year-old.
The two boys lived in different parts of the country and never met, but the similarities between them strike their mothers daily.
Zoe says: 'I see little things Anna writes on Facebook and think, 'I can definitely see that in Roman.'
'Logic tells you it's not possible, but there are weird things that happen. Anna put up on Facebook that Fraser used to love the song Forever Young.
'Whenever that song comes on, Roman sings it. I don't know how he knew the words. I'd think, 'How have you even heard this?'
'I don't know if it's me reading too far into it, but it's like deja vu. We always say, 'He's been here before' or, 'He's done this before'.
'And it's simple things, like Fraser used to love football and playing air guitar. Roman has always played air guitar. How would he have learnt that in hospital [where he has been for so many months]?
'There's also this football side to him; I haven't pushed football on either of my boys.
'When I said we were going to meet Fraser's mum, he was so excited. Like he just knew he'd have that connection.'
Zoe, a former teaching assistant, learned Roman had a serious heart defect at her 20-week scan. She was offered a termination, but refused. She loved her boys dearly and would do all she could to give them both life.
There was a team of 56 doctors, consultants and specialists to assist when the babies were delivered in a planned C-section on her 25th birthday. Tests confirmed Roman, who weighed 5lb 7oz, had an under-developed right side of his heart.
He would require a heart transplant and several operations to survive. Zoe and her husband, Craig, who have since divorced, spent ten months at the Freeman Hospital in Newcastle as their little boy had 'surgery after surgery' and waited for a heart.
Spring turned to summer to winter and Christmas approached. In Cardiff, Anna-Louise and her family were caught up in the festive cheer.
That fateful Saturday in December they'd had 'such fun' at a Christmas party. The next day, Stuart, an IT manager, was to be Father Christmas at his little daughter's nursery school.
Shortly after midnight, father and son, hand-in-hand, began to cross the road in leafy Talbot Green.
The car that hit them did so with such force, both bodies suffered catastrophic injuries.
Joshua Staples, 22, was later jailed for 16 months after admitting death by careless driving.
'When they asked about donating Fraser's organs, I didn't hesitate,' says Anna-Louise.
'We'd had a family conversation about organ donation over dinner two weeks before. Stuart and Fraser both wanted to be donors. Fraser always wanted to help people.
'He was transferred to Bristol Children's Hospital. It's only now, understanding the procedures of organ donation, I wonder how he survived that journey.
'I think what a superhero he was, because that gave me time to get the strength to say some proper goodbyes before donating his organs.
Anna-Louise's husband Stuart (pictured with Fraser and Elizabeth) also died after being hit by the car. Joshua Staples, 22, was jailed for 16 months after admitting death by careless driving
'When he was on life support he looked so calm, so peaceful. When I was doing the paperwork for the donation, it was so hard because he was still breathing. I just kept going back and forth to say goodbye.
'My head hadn't gotten round to the fact I wouldn't actually see him again. It still hasn't. The hardest thing I've ever done was leaving him still breathing in the hospital.
'When I got the call that Monday, I knew he was finally at peace and that his heart had carried on beating long enough to actually give life and love.'
That same morning, Zoe received a call at 7am from a nurse at the Freeman Hospital to say they believed they had a heart that would be a match.
'It was December 7. I'd got so used to waiting, we'd just made a life in the hospital. When the nurse called, I'll never forget it. I got to his bedside and didn't let him go until they finally took him off at 3.30pm [when the heart arrived from Bristol].
'They explained the little boy he was getting the heart from was bigger than him. Normally, they only go three sizes bigger than a child's heart. This heart was four sizes bigger, but the match was too perfect not to take a chance.'
For a week after the nine-hour operation, it was touch and go whether Roman would survive. He suffered internal bleeding and a collapsed lung but, throughout it all, Fraser's heart beat strongly.
'They left his chest open for seven days with cling film across so they could see what was happening to his heart,' says Zoe.
This measure was in part to prevent the heart being compressed, and to allow medics access at a moment's notice if necessary, without the trauma of reopening the small boy's chest.
'There were wires, like a bootlace, attached to syringes, and every couple of hours they turned the syringes to slowly bring his chest together,' says Zoe.
'I sat with Roman watching Fraser's heart beat. It was like feeling every emotion all at once. I was overwhelmed Roman had a chance of life but so sad someone had lost their little boy for mine to have that chance.'
As she sat in that Newcastle hospital watching the beat of the heart that would give her precious boy life, in Cardiff Anna-Louise was setting up the organ donation charity Believe, in memory of her son and husband.
It was, she says, born out of the 'luxury' of having that conversation with her family just before the accident.
'I knew what my boys wanted,' she says. 'I hoped the charity would help other people to have the same conversation so that if this happened to somebody else they'd know what to do.'
The law around organ donation changed last year so all adults are now considered willing to donate unless they opt out, but parents must still provide consent for children under 18.
'It helped me do something positive,' Anna-Louise explains.
'The dark times are always there. It was the Sunday nights when everybody else was going about their family business. We'd shut the door and it was just Elizabeth and me and the loneliness and the missing because our house was always full of noise.'
That week in Newcastle, as Roman recovered, Zoe read the many newspaper reports about Anna-Louise's heartbreaking loss and her determination to make something good of it with her charity.
Organ recipients are only allowed to contact their donor through a third party after a year has passed. Even then, scant personal detail is permitted.
'I began to wonder when I read about Anna's story two or three days after Roman got his heart,' says Zoe.
'Fraser always wanted to help people': Anna-Louise said she didn't hesitate when they asked about donating Fraser's organs as both Stuart and her son (all pictured) wanted to be donors
'I went into the hospital and said, 'I know you're not allowed to answer my questions. I know I'm not allowed to know where it's come from. But just you saying it was not the usual size — can you nod or anything if I said did it come from a seven-year-old boy?'
'One of the nurses had a sort of little grin on her face. I thought, 'I know it's him.' '
Such were the complications following Roman's transplant, including numerous infections and liver and spleen problems, Zoe only sat down to write to Anna-Louise in 2017. She tried 15 times before she found the right words.
'When I'd finished the 15th version, I sent it to the transplant nurse, saying, 'Can you read it to tell me if everything's OK? If it is, send it because I can't write another.' '
Anna-Louise received the letter shortly before Christmas.
'I remember going to events for organ donors and recipients through my charity and thinking, 'One of Fraser's organs could be in this room,' ' she says.
'I'd just taken Elizabeth away for the second anniversary [of Stuart and Fraser's deaths] when I got the letter from Zoe.
'Boy, did that letter help me get through Christmas. The wording she used gave me so much comfort. She said by donating my boy's heart I'd saved her boys. There was a brother. Therefore, two boys' lives being lost, Stu and Fraser, had assisted two boys.'
The letter Anna-Louise wrote back hangs on the wall in Zoe's sitting room.
'Fraser (my son) really did have the biggest heart,' wrote Anna-Louise. 'He was older than his seven years, had the sensitivity for a boy that was unmatched. He was best friend to everyone whatever their ages.'
Since those first letters four years ago, Anna-Louise and Zoe have continued to write to one another after later making contact through Anna-Louise's charity.
Zoe wanted to introduce her son to Anna-Louise, 'mainly for a little bit of peace for her to see he's doing well. It's not all in vain and something good has come from this.'
Anna-Louise finally felt she was 'ready emotionally to deal with it' this year. She knew Roman was poorly (he'll receive his father's kidney next year) and worried 'if I didn't meet him, how would I feel then at that child's loss?'
They agreed to meet last week.
'We were walking down the stairs, I saw her and thought, 'Oh my God, there she is,' ' says Zoe. 'Roman just took off. They took to each other instantly.'
Much has changed in the six years since that terrible December night. Anna-Louise has remarried after meeting her husband, Zach Stubbings, through her charity, while Zoe is also mother to three-year-old Bear and a baby daughter Pixie with her partner Ryan Johns.
They are here today with Fraser's sister, Elizabeth, now nine — strangers until this week and now united by a seven-year-old boy's wish to help others.
'When I was pregnant with Fraser, I remember saying to the midwife that I was really worried how I was going to love this child as much as I loved my husband,' says Anna-Louise, with Roman on her knee and her eyes full of joy.
'She said, 'Another piece of your heart grows that you never knew was there.'
'Fraser will always be a part of my heart, but I feel like another part has grown for Roman and his family. Fraser is a part of that, too.'