Explanation: Themistocles, a radical democratic politician of Athens, and a military commander of great influence and achievement during both the First and Second Persian Invasions of Greece, was exiled in later life by the same Athens he had so loyally served. Ironically, this was in part engineered by the Spartans, who disliked his radical democratic view, but largely the result of Themistocles making domestic enemies and rivals.

With nowhere in Greece to go, he sailed to his old enemy - the Persian Empire - and offered his service to the grandson and son of the Persian kings whose invasions he had thwarted. Artaxerxes I, said son and grandson, gave him a chance to make his case.

While acknowledging that it was a fucking wild move, Themistocles presented his position with the rhetorical skill of a seasoned demagogue, and promised that, as he had no homeland left, he would serve Artaxerxes with all the skill he once opposed Persia with. Artaxerxes was overjoyed to have an old foe of such illustrious reputation to support, as Artaxerxes’s policy towards Greece was to weaken Greek colonial expansion by keeping them divided and quarrelsome, and welcomed Themistocles warmly.

Themistocles would learn Persian language and customs, and serve Artaxerxes faithfully in the capacity as a governor and advisor, becoming a key part of Artaxerxes’s court. Athens would later realize what a dipshit and ungrateful move exiling Themistocles was and rehabilitate his reputation as a hero, but by then Themistocles was dead of natural causes, and thus… could not return to Athens.

If he did that, yeah you want him on your side.