Do you mean working backwards so no matter what happens i'd end up with a few ''ending'' possibilities? and by ''converge'' wouldn't that make a dna effect? meaning it'll branch out then come back in then branch out again?
Yes, exactly. By having the events all come to the same few endings it will really make the game come full circle rather than feeling open-ended. And yes, converging events would create that effect.
Another thing which would greatly help the sense of unity is to create several large scale events which occur in the world and are somehow tied to the overarching story line. These large scale events would occur no matter what path you're on, but the path you've chosen will effect how you interact with those events. For example, imagine that at a fixed point in the timeline there's an army which attacks a city. Depending on your current branching path, you may find yourself in a number of positions. Perhaps you're at the front lines of this attacking arming, or maybe you've enlisted in the militia of the city and are defending it. Or maybe you just happen to be strolling through the city at the time of attack. Or perhaps you're in a distant land altogether and you only hear word of the attack. Or maybe you've found a way to prevent the attack before it even happens, such as by helping form a truce of some kind.