I've never had a game in 867 where the Holy Roman Empire actually forms. I've played dozens of games as the Byzantines for a century or two, and not once have I seen it formed. I think it should be tweaked in some way that they ai is actually able to form it at some point. I thought for awhile it was just me, but after so many games using various updates of HIP since the first version it almost think it is impossible. In my opinion the HRE should typically form by the 10th century, unless the player is actively trying to make it not happen. I usually play as the Byzantines, and I never mess with Western Europe at the start. Sometimes I even use the console to give one of the Karlings a bunch of money and have them declare war on whatever they need to form it. Still, nothing has worked. For this entire year, even before the mods were put together into HIP, I have not once seen the HRE form. Can anyone tell me if this is common?
This is kind of weird for me to hear. It's probably just that I rarely,
rarely play the 867 start, but it seems common that when I do, the HRE manages to form ridiculously fast (or not at all-- perhaps the dichotomy is intentional). Random number generators...
Here's the thing, though: why don't you play in Western Europe and try to form the HRE? If you can do so, contrast that with what you see the AI do instead in your games, and perhaps we can take something home from that.
I will say that influence over the AI and war targets is very, very difficult and something which we can hardly control (under plausible, non-forced sandbox gaming circumstances), though. As others have said, it's kind of surprising that the HRE
did happen. We aim for accurate starts and plausible playthrough. If the HRE actually is a long shot for various reasons which are not plausible to control, then I suppose that may just be a fact of life. However, given that I've seen it happen more than once, there's probably something that could be done to affect the likelihood.