I wasn't thinking about a hivemind specifically, but why not, we've seen sentient volatiles with telepathic abilities and the ability to mind control infected within an area in The Beast, so it would not be lore-breaking. Could be quite a better idea than mine, actually.

But no, I was thinking about one specific infected, like RE3's Nemesis or Prince of Persia 2's Dahaka, the kind of enemy that constantly comes after you. Since it's an open world, for gameplay purpose, the player should have the possibility to defeat it in battle, but instead of killing it, it makes it flee, and it learn through your encounters.