Originally Posted by
War Machine Dawg
Yes, that's the irony of Tywin's hatred of Tyrion. The whole theory that Tyrion is the bastard of the Mad King & Joanna Lannister is a red herring. It's really Jaime & Cersei that are bastard Targaeryens - Blackfyres. It's heavily foreshadowed in Cersei's story. Tyrion is the only real Lannister and Tywin's legitimate heir.
The key in GoT/ASOIAF is this line: History doesn't repeat, but it often rhymes. I don't remember the corollary rhyme from the history, but their was a story where a son unknowingly killed his father to save the realm. That's what happened with Jaime & Aerys. Jaime unknowingly slew his father to save King's Landing and the people. Cersei's rhyming story is going to mirror that of Alison Hightower, the Dowager Queen (look it up).