In my current game I started as the Petty King of Nubia with the goal of trying to create the most powerful realm of united Christendom I could*. To this end I needed to spread out over Abyssinia. Initially I focused on creating the Kindgom Of Nubia, successfully doing so after pressing a few quick county claims to gain territory. I then decided to test my might against the Sunni Muslims to the North, being driven back humiliatingly by an alliance of several duchies to protecting their heathen faith. Embittered by this loss I turned my eye back to the South-East, towards my neighbours in the De-Jure kingdom of Abyssinia. I swept past the native Ethiopians to attack the Muslims on their far side, claiming several counties for myself, then settling down to wait for an opening on more lands.
My good fortune provided me with a way to seize the lands of Abyssinia from it's rightful rulers. The King had betrayed the Coptic faith, embracing the Monophysite heresy. Given this opportunity I stormed into his lands to reclaim them for the Virgin Mary, eventually seizing enough that I could usurp his title, but of course he was a heathen, and thus I could not usurp his titles. Then he died, his first son was also a heathen, but he was incapable and short lived as a ruler, serving only to be stripped of more lands by me. The second son of Abyssinia was not a heathen however, and I was able to usurp his throne and vassalise him. Leaving me as the sole ruler of the two Kingdoms.
Once again I turned a baleful eye towards the lands of Egypt to the North. Now with my armies filled with the wrathful armies of Nubia and Abyssinia I crushed the first duchy in my path. An attempt to seize Alexandria as well failed, once more the Muslim foe had banded together to deny me my prize.
Disheartened, but ambitious, I managed to arrange a matrilineal betrothal between my firstborn daughter and the grandson of the Basileus of Byzantium, and betrothed another daughter to a prince of Lombardy. Both realms welcomed my request for a formal alliance, and with their backing, and the help of Nubian and Ethiopian mercenaries the duchies of Egypt crumbled before me, opening the way for the creation of a holy order dedicated to the Miaphysite faith.
I then swept my gaze East, towards the heaving bulk of the Abbassids. I knew that the next step in creating the most glorious of Christian Kingdoms would require the envelopment of the Nestorian faith, and their Holy Lands lay in the hands of the Caliph. My armies clashed with theirs, and would have faltered and failed were it not for the service of my mercenaries, my new holy order and the vast armies of Byzantium. The Caliphs lands were already embroiled in a civil war when my men arrived, and both rebels and liege were swept from the South-Western lands of Arabia by the glorious men of god. The Abbassid's were eventually shattered by the rebellions that squirmed inside their land. New petty kingdoms took it's place, each but a shadow of the power of the old Caliphate. Easy prey for my further conquests.
It was during this time that I converted to the Nestorian faith, losing the service of my Holy Order, and began to fabricate a claim on Rome, receiving one in a mere few years. Rome was easily conquered, the Pope a weak and unprepared opponent.
I ultimately found myself holding the lands of Baghdad, Jerusalem and Antioch. If I could return the peoples of these lands to the ways of Christ yet another Holy Order would rise from the ashes of the heathen's pyre to lend me their blades, and, after a decade of preaching and heathen uprisings at last those lands saw the light.
My duty to the Nestorian faith complete, I took up the mantle of the Orthodox faith, intending to prepare my lands for my heir, for she was the wife of the Byzantine Emperor at this time, and her sons, heirs to the Empire were of my dynasty.
Not long after I passed away. In my 60s, ruler of the Abyssinian Empire and restorer of two ancient orders of Christendom.
It falls to my grandson to continue my work on uniting the children of Christ. I have left him a good legacy with which to wage a great war of the faith. He may lack my stength of faith and will, but I believe he will end the divide between the christian peoples of Europe and Africa.
*One of my mods make Mending the Schism roll Nestorians and Miaphysites into Orthodox as well as Catholics, so all Christians are one thing once the schisms is mended.
All that wound up
waaaay longer than I originally intended.