It was surprising how quickly I managed to recover House Hightower after what was essentially an inter-family civil war lasting 3 generations. I'd falsified claims and married off children to make us High Lords of Oldtown and the Westmarch, but I'd installed Hightower family members as the lords in each county. Retrospectively, this was rather foolish of me, as now all my vassals had claims on my main titles.
All was actually going fine and dandy, until one of my grandsons (aptly named Rorge) made a foolish matrilineal marriage, which I didn't realise until I was playing as his father. So then I had to assassinate both his wife and his sole heir, which due to some weird succession law on his wife's side, meant he was now skipped over in the succession and my second son Denys was now my heir.
So I died in a trial by combat (most of my Hightowers have died in some form of combat or were murdered) and then Denys inherited my titles. Unfortunately, Rorge wasn't too happy about this and declared war on me. He was promptly joined by nearly all of my Hightower vassals and quickly won the war then imprisoned me (Denys). By some twist of fate, I had managed to have a son, Preston Hightower, just before I was captured. This turned out to be key since suddenly my aunt Aglantine Hightower claimed the High Lordship of Oldtown and declared war on my brother Rorge. He lost this war, and became known as the rather menacing sounding Ser Rorge Hightower, holder of some ill-begotten castle.
Now I'm not sure what happened here, but my Aunt died of old age, and then suddenly my son Preston became the Lord of Oldtown by some weird result of succession laws that I have yet to fully understand. I was still imprisoned by Ser Rorge in his keep, but as Preston was my son and my only child I was also now his heir.
Ser Rorge then assassinated Preston, which made me the High Lord of Oldtown again even though I had been in prison for the last few years. He then became my heir and when I died in his dungeons and he became, for the second time, Lord Rorge Hightower, now controlled by me. Now after this, Rorge had both a son and a daugher who died of pneumonia when they were young, which meant that his second daugher Ermesande became his heir. Ermesande had been betrothed matrilineally to some young Tyrell lordling who was leftover from a previous plot to acquire the Reach (the Tyrells were no longer Lords of the Reach at this point, it was the Rowans).
Rorge was then killed and at the age of 6, Lady Ermesande Hightower became the ruler of Oldtown and the Westmarch. During the Hightower Civil Wars, it turned out that we had lost a sizeable chunk of land from our demense. Ermesande through her regent, instigated several quick wars to retake these provinces and then began a plot to acquire the Reach once she was of age.
As it turned out, most of our fellow Lords and Ladies did not like the Rowans being Lords Paramount, especially the young girl we had as our liege at the moment. We garnered over 400% support on the plot and then sent a threatening letter to our liege lord, and quick as you know it, she abdicates the Reach (she was also Lady Paramount of the Stormlands as well, so not all was lost) to Lady Ermesande.
Ermesande managed to have one son, Balon, before dying a natural death at the age of 33. Lord Balon took no time at all in declaring House Hightower as Kings of the Reach, outside of the realm of the Iron Throne and the Targaryen king. This was in the midst of some civil war, so we quickly subdued any armies against us and won independence.
King Balon I was not so clever though and he was murdered by a vassal fairly young, leaving only his two sons behind. The first son married off his brother, also called Balon, to the Queen of the Kingdom of Mountain and Vale (the Vale and the North) to secure an alliance. It's also good to point out that for around 100 years, the Lannisters have ruled the smallish Kingdom of the Rock (which was actually established by House Crakehall originally) independently, as have the Arryns as the Kings of Mountain and Vale.
Anyway, Balon's brother King passed away fairly young as well, leaving King Balon II on the throne of the Reach. Balon II murdered his wife, leaving his only son King Gilwood of the Vale, whose heir then happened to be Balon II. Thus King Balon II murdered his son as well, unifying the North, the Vale and the Reach under one banner in his 20s.
That's where the story ends, though it turned out Balon II was a pretty massive badass even in his 50s, as demonstrated in this screenshot during the period we were invaded by the Iron Throne over their claim on the Westmarch.
http://cloud.steampowered.com/ugc/577835582257480906/340D2DCD8ABE5549E5B03B7CCE9E3C2B291D5F98/
Yes, he slew the Targaryen king in combat during a massive battle. He nearly slew his son King Haegon as well a few weeks later, but was maimed and never recovered from his injuries.