There are those who support the idea that Tyrion is a Targ; but there are also those who believe Aerys fathered Jaime and Cersei, which would mean that a Targ is already on the throne (Tommen) and he succeeded another Targ (Joffrey).Just a quick pointer - is it my imagination or did I read something suggesting that Tyrion could be a Targ?
Wasn't it mentioned that one of the Targ kings had spent time in Casterly Rock less than a year before Tyrion was born?
I seem to recall the implication was that Tyrion was a Targ, but I really can't remember if it was something I noted reading, or a discussion on this forum.
If he were, though, the three heads of the dragon would be the three last remaining Targs:
Dany
Jon (assuming R+L)
Tyrion
Aegon as a red herring.
Just thinking out loud here.
Perhaps all three are Targs, allowing Jaime, Cersie and Tyrion to be the three heads of the dragon.