Coach Campbell and others, Inside zone weak

Lets say were in the I formation pro set and inside zone weak is the play. The D has a 1 or 2i and a 5 on the weakside. You want a duece by the center and guard on the 1 or 2i to the playside backer in this case the weakside backer. The tackle will block the 5 tech out. What does the fullback do??? block playside or backside?? combo with the tackle on the 5 tech??