4 years

This may have been covered previously, but I'm gonna ask again anyway.

Why is it that EVERYTHING happens 4 years ago? The Uroyoms (sp?), the TF gun, the sprinklers in the school, etc....

Everything happens 4 years ago. Is that just a convenient number that Dan is pulling out of his hat, or does it have some significant meaning?

If it was three years I could relate it to US society, which does everything in threes. Four...all I can think of is that it usually represents everything, or the entire world.

Four compass points
Four winds
Four corners of the globe
etc etc

Four years is the standard length of high school; it means that except for those who have been held back, there are no students at Moperville High who were there to witness any events that happened four years ago...

(No, I don't think that's the real reason; just indulging in idle fantasy.)

Four years ago was about the same time that Mr. Verres was trying to free Grace and her brothers. Since Tedd didn't know about this in the first few comics it probably won't come up directly. But there might be some clues spread out in the flashback.

Well, the TF gun and the Uryuoms coincide because the former came from the latter. And it's evident that they weren't new to Mr. Verres, only to Tedd.