A 25th birthday night in ended in a knife attack leaving one woman dead and her two sisters and father seriously injured, a jury has heard.
Tyler Denton had been celebrating her partner Hayley Barnett's birthday with Shannen and Cody Denton at the home she shared with her friend Redvers Bickley.
Mr Bickley, 21, allegedly launched the attack in Rhyl, Denbighshire, after feeling angry he had been left out.
He denies murder and attempted murder at Mold Crown Court.
The trial heard how Mr Bickley loved Tyler and was obsessed with her.
He had been drinking alcohol on the night of the attack on 9 September, the jury was told, and became angry after reading text messages Tyler sent to her girlfriend about him.
The sisters had left the house for a few hours and when they returned Mr Bickley was bleeding, having cut his hand on broken glass.
The court heard the sisters started to clean it up but Mr Bickley became annoyed and said "let's begin" in a strange, deep voice, before launching his attack.
He sliced Cody's right cheek with a knife, pushed her to the ground and continued to strike her.
He later attacked Tyler before moving on to Shannen, stabbing her in the back, head and neck as she lay on the ground, the jury was told.
John Philpotts QC, prosecuting, said: "This time the stabs were controlled and deliberate. He knew exactly what he wanted to do.
"He was saying things like 'Red's back', 'Red's revenge' and 'Red's return…'."
As Shannen lay on the floor, she telephoned the sisters' father, Paul Denton for help, while Cody moved Tyler into bushes where they hid from Mr Bickley.
'I killed someone'
Their father arrived and was attacked as he went to protect his daughters, the jury was told.
But with Cody's help, he overpowered Mr Bickley and, after a struggle, he detained him.
The trial heard that as he was arrested Mr Bickley told officers: "I killed someone" and later, in a police car, said: "Do you know how hard it is to love someone and not have them love you back?"
Tyler died in hospital and a post-mortem examination showed she had eight stab wounds.
Mr Philpotts told the jury that although the relationship between Mr Bickley and Tyler was like that of a brother and sister, it appeared he wanted more.
During police interviews, the court heard Mr Bickley said his life had been on a downward spiral and he spoke of a different side to his character, which had "dark thoughts", including killing people.
Mr Bickley denies murder and three alternative charges of wounding with intent to cause grievous bodily harm.
The trial continues.