The 20-year-old victim was sleeping in his bed when his father repeatedly hit him over the head with a hammer. When his mother attempted to stop the brutal attack, her husband turned on her.
Police were called to their residence outside the Costa Blanca town of Denia on Sunday morning after neighbours heard screaming and saw the man struggling his wife in the doorway of their home.
When police reached the property they said they found the aggressor covered in blood and still carrying the hammer.
A trail of blood led officers to the bedroom where they found the couple's son lying in bed with “serious head wounds”, according to a statement from the National Police.
He was taken to hospital where his injuries are described as “serious but not life threatening”. His mother was also treated for injuries.
The suspect, who has not been named, was remanded into custody without bail on Wednesday by a magistrate at court in Dénia and could face charges of attempted murder.
Although no motive for the attack has yet been given, investigators are considering the possibility that the aggressor “suffered a psychotic episode”.
According to news agency Efe, the couple and their son were not on holiday but had been living in the area for at least five months.