Transit Police spokeswoman Anne Drennan says the suspect had consumed alcohol with her 28-year-old former boyfriend on Friday afternoon and evening and then followed him onto a bus when he left Langley.
Drennan says the two argued on the bus and the suspect again followed the man onto the SkyTrain, where the argument continued.
She says that as the man stepped onto the platform at a Surrey station, the teen stabbed him in the leg and that he also sustained defensive wounds to his hands and a cut to his forehead.
Drennan says the suspect then ran through an emergency exit and was apprehended on the stairs by Transit Police, who recovered a steak knife.
The victim has been treated in hospital for his injuries, and the teen is scheduled to appear in provincial court on Monday.