Arthur Labinjo-Hughes' uncle told a court today the boy's stepmother was 'cold and calculating' and 'domineering' and that she was the 'catalyst in his murder'.
The six-year-old from Solihull, West Midlands was killed by the couple after suffering abuse 'designed to terrorise', it is said.
The youngster was allegedly deprived of food, made to stand in a hallway for 14 hours a day and poisoned with salt before being fatally attacked at his home in June 2020.
Thomas Hughes, 29, and Emma Tustin, 32, allegedly subjected Arthur to 'systematic, cruel behaviour' which met the 'medical definition of child torture'.
Hughes and Tustin deny murder. Tustin has admitted one count of child cruelty but denies three other counts. Hughes denies four counts of child cruelty.
Six-year-old Arthur Labinjo-Hughes was weakened by months of abuse, salt poisoning and starvation, prosecutors claim (pictured with father Thomas)
The distressing footage was shown to jurors at Coventry Crown Court on Tuesday, where Thomas Hughes, 29, and Emma Tustin (pictured), 32, are accused of killing Arthur at their home in Solihull, West Midlands, last June.
A trial at Coventry Crown Court today heard evidence from Arthur's uncle, Andrew Hughes - the brother of Thomas Hughes.
He told jurors that he believed 'cold, manipulating, calculated' Tustin was the 'controlling partner' in the relationship, and the 'catalyst' of Arthur's death.
Mr Hughes, 26, described the mother-of-four as being 'domineering' both towards Hughes and Arthur.
He told jurors: 'If she didn't get things the way that she liked, she would make things hard for everyone involved'.
Schoolboy Arthur died in June last year from 'unsurvivable brain injuries' while in Tustin's care.
She is alleged to have killed Arthur using 'very severe force' while she was alone with him at her council house near Solihull.
Hughes is alleged to have 'intentionally encouraged' the killing. The pair are said to have subjected Arthur to 'violence and intimidation' in 'brutal controlling circumstances'.
It is claimed he was poisoned with so much salt that medics questioned their machinery when he was admitted to hospital with fatal brain injuries.
Jurors were told how Arthur had been in the full-time care of Hughes after his mother Olivia Labinjo-Halcrow was accused of killing her new partner, Gary Cunningham, in February 2019.
Hughes then met Tustin on an online dating site in August 2019.
Giving evidence, Mr Hughes said he felt the relationship moved 'too quickly' because 'they didn't know each other well enough'.
Describing his first meeting with Tustin, Mr Hughes said: 'I tried to be friendly, I tried to introduce myself, I tried to have a laugh.
'She was very, very cold. I got very little back from her.'
Hughes moved in with Arthur to Tustin's council house in Cranmore Road, Shirley, when the country entered lockdown in March 2020.
It is alleged that Arthur was made to stand up for 14 hours a day in a hallway 'all day, every day' for up to six weeks.
Jurors were played footage from a living room camera of the boy making a makeshift bed on a living room floor.
Tragic Arthur Labinjo-Hughes, six, attempts to pick up duvet from floor where he slept in CCTV footage shown to Coventry Crown Court on Tuesday
Jurors were previously told how Arthur (pictured) was 'repeatedly poisoned with salt-contaminated food and fluids' in 'brutal controlling circumstances'
The jury was previously told Arthur's family raised concerns with social services two months before Arthur's death. But after a home visit no further action was taken.
Mr Hughes told the court that Arthur seemed 'far more timid' when he last saw the youngster a week before lockdown.
He told jurors: '[Arthur] seemed more aware that he may get in trouble.
There was this voice that Arthur would sometimes make - he would refer to it as his baby voice.
'Beforehand that was never an issue, but it became an issue not long after Miss Tustin arrived on the scene.'
He told how Hughes was 'very open, very warm' before meeting Tustin and 'believed strongly in the family unit'.
He said: 'Over the course of the relationship Tom's behaviour and his mood significantly altered, yes.
'We would argue more over minute, menial things.'
Asked by Hughes' barrister, Bernard Richmond, how Hughes appeared after meeting Tustin, Mr Hughes responded: 'He went into himself with his family - mum, dad and his brothers.
'The ties became weaker and weaker, and he didn't seem as invested in keeping that structure strong.'
Arthur was found with 125 areas of bruising on his body after dying from unsurvivable brain injuries on June 16, 2020.
The boy was said to have been denied water and food and 'deprived of basic living comforts'.
Prosecutors claim Tustin shook and then slammed Arthur's head on a hard surface while alone with him.
She claims the youngster died from self-inflicted injuries, a theory rejected by medical experts.
Hughes is alleged to have 'intentionally encouraged' the killing.
Text messages sent to Tustin included remarks by Hughes to 'fill him in', 'take his neck off his c***ing shoulders' and 'get nasty'.
Tustin was also told to 'give him away' and 'put him out with the rubbish', jurors were told.
In a message sent 18 hours before Arthur was allegedly murdered, Hughes told Tustin: 'Just end him'.
One witness claimed in court that Arthur was 'too weak' to even hold a glass of water to his mouth on the day before he collapsed.
They also said his clothes looked dirty, his lips cracked, he could barely open his mouth to speak, his hair was dirty, his nails were dirty and he looked malnourished, gaunt and worn-out.
Earlier in the trial, a medical expert said he believed Arthur was shaken and slammed with 'very severe' force.
Consultant neuropathologist Daniel Du Plessis said the chances of Arthur causing himself fatal head injuries were 'inconceivable'.
Opening the trial, Mr Hankin told jurors: 'Both defendants participated in a campaign of cruelty intended to cause Arthur significant harm and suffering.
'Violence and intimidation, both physical and verbal, were routine.
'Arthur's visible injuries, his miserable physical condition and obvious despair provided each defendant with a daily reminder of the lengths to which the other would go to cause him harm.'
The trial continues.