For those who don't know, Cannibal was a ''wild'' dragon on Dragonstone who was never tamed and was infamous for devouring other dragons, most often baby dragons and eggs.
He never took a rider and was one of the few dragons who survived the Civil War (The Dance), what happened to him none knows, but he basically just vanished one day never to be heard or seen again.
Now, having angry Dragons isn't uncommon, but having a dragon who eats other dragons and shows nothing but hatred for everything around him is incredibly bizarre. In fact I think Cannibal is the only dragon to ever express such odd behavior for no real reason.
I can understand him not taking a rider but why would he eat his own kin?
I mean yeah he wasn't the only ''wild dragon'' but there is no doubt that he was the only one who went out and ate other dragons and just couldn't be tamed no matter what.
One theory is that the he wasn't from the same lineage as the other Dragons on Dragonstone, so he didn't consider them his ''family'' which explained his aggression. Maybe he wasn't from Valyria or originally wasn't descended from the group of dragons that came to the island after the Doom.
One thing that is interesting is that he was one of the oldest dragons on the Island by the time of the Dance.
He was alive before ''Sheepstealer'' (Another wild dragon) and this dragon hatched when King Jaehaerys I Targaryen was a young man. And this guy was one of the longest living kings that Westeros even had.
So none knows the exact age of Cannibal, some say that he was present on Dragonstone before the Targs even arrived all those years ago, but this seems unlikely.
There is definitely a mystery here and I'm interested in what you think the explanation is.