Events of Red Dead Redemption 2
Tavish is first seen at Caliga Hall talking to John Marston, Javier Escuella, and Arthur Morgan about Catherine Braithwaite's prize horses, and promises them that a man will give them five-thousand dollars for them, if the gang manages to steal them from Braithwaite Manor. This promise later turned out to be false, as the gang were only paid seven-hundred dollars for the horses.
Tavish and Leigh later plotted revenge on the gang for burning down the Gray family's tobacco fields. The Grays offered the gang a security "job", resulting in a battle in Rhodes and Leigh's demise.
Sometime after the battle, Tavish presumably committed suicide, as his body can be found on the back porch of the main building in Caliga Hall as a point of interest, next to a letter that proves his proud Scottish heritage is not quite what it was thought to be.
Red Dead Redemption 2