Jamie Yeates had a "realistic ambition" of becoming a jockey
A "bullying, controlling" man murdered the teenage stepson he hated in an unprovoked knife attack, a jury heard.
Swansea Crown Court was told Jamie Yeates, 15, of Grant Street, Llanelli, had been asleep in bed when his drunken stepfather attacked him.
Carl Bowen, 42, denies murdering his stepson. He also denies the attempted murder of his wife and stepdaughter, and two alternative charges.
Jamie was said to have been stabbed 18 times in the early hours of 8 January.
Elwen Evans QC, prosecuting, alleged that Mr Bowen refused to feed Jamie, encouraged the other children to assault him and went for months without even talking to him.
Ms Evans said Jamie and his sister Kimberley, now 19, had both been banned from having any contact with their father's family.
But when Jamie's grandfather developed cancer the two got back in touch and Jamie began visiting.
Ms Evans described Mr Bowen as "possessive, jealous, controlling, bullying and manipulative".
His wife Maria, a care home worker, had also been banned from speaking to her own parents.
Mr Bowen continually suspected his wife, who had seven sons by him, of having affairs, said Ms Evans.
He banned her from leaving the house without his permission, timed her visits to the supermarket, checked her mobile telephone and examined the mileage on the family car.
"He was a possessive, jealous, self-centred man who expected his own way and drank to excess," she added.
The court was told how Mr Bowen spent 7 January drinking gin and orange. In the early hours of the following morning, he suddenly went to Jamie's bedroom with a kitchen knife.
Ms Evans said it was a "brutal and vicious assault" on a sleeping, defenceless 15-year-old boy, who bled to death.
Ms Evans said Kimberley and her mother heard Jamie shout one word, "Mam", and left their bedroom.
The court was told that on the tiny landing outside, Mr Bowen stabbed Kimberley twice to an arm and tried to butt and stab his wife, but she escaped.
Mr Bowen denies murder, and two charges of attempted murder, as well as lesser alternative charges relating to his stepdaughter and wife.
The court heard that Jamie had a "realistic ambition" of becoming a jockey and had been working for a race horse trainer at stables in Carmarthen.
The trial continues.