I’m assuming that your grapple component is added to the Patrol Guard at start. If so, then you can use the Event Receive Execute AI event to get your controlled pawn. Just cast it to the required AI class and you should be able to get all the components.
Regarding the damage application, I’m assuming that you have implemented your own Health system in the player character blueprint. When the health reaches 0.0, you’d have to call the ReportPlayerDeath function from Game Mode. That should bring the game over screen.