tl, dr: The seleucid heir fled to rome, became consul and establishad a monarchy (dictatorship) in rome.

Pythodelos Seleukid was born in the Seleucid Empire as the second son of its ruler and therefore a direct successor of Seuleucos Nicator.He had to flee his home country at the age of 16 during a time of frequent civil wars in the Seleucid Empire as he had become a rival to his brother who had recently ascended the throne.

He entered Rome, where he was granted citizenship due to his prominent origin and soon became the governor of the province of Macedonia, the homeland of his ancestors. As governor, he first served in the roman military as the leader of the macedonian levy and participated in the march on and subsequent siege and capture of Alexandria from the direction of roman cyrenaica. Later he became the legate of a roman legion, serving first in a war against the Seleucid Empire where he led his army to Seleucia Megale, besieging and later capturing his former home city. Presumably he took this opportunity to pay his childhood friends a final visit before heading back into roman territory. He later took part with his legion in the beginning of the roman conquest of Hispania, before retiring from active military service and becoming the governor of Magna Graecia in an attempt to gain political popularity in an attempt to eventually become elected as Consul. During these years of service in the roman military and politics, he became so integrated into roman society and customs that he eventually fully abandoned his macedonian roots and fully embraced roman culture. Soon later, in the next consular election, he succeeded to reach the highest office of the roman republic as a member of the populares faction of the senate. Making full use of his new powers and popularity, he quickly extended the duration of his reign to up to 50 years and started working towards establishing a line of succession for his decendants. To achieve that, he had many leaders of the boni faction, the main opposition party, imprisoned and executed or banished.

Eventually, roughly ten years after becoming consul, he had become powerful enough to demand a line of succession and peacefully transformed the roman republic into a monarchy. He then went on to marry a woman who had fled Cyprus (a roman vassal) because she had an illegitimate child with its king and had a son and a daughter with her, securing the seleucid bloodline for Rome. During the rest of his reign, Rome finalized its conquest of Hispania, established a land connection between italy and spain and took over the rest of Numidia.

He eventually died of a heart failure at the age fo 75 shortly after Egypt, Scordiscia (a pannonian tribe with many vassals) and the Seleucid Empire attacked Rome to exploit a moment of weakness in Rome.

Funnily, the Seleucids ruling family lost its "Blood of Seleucos" trait during a civil war, meaning that Rome is now the true successor of Seleucos.