The Boy-King, the Macedonian, the Emperor of Persia and Pharaoh of Egypt. The Hegèmon, unquestioned ruler of the Empyraeum. The Son of the Dragon.
Alexander, there has been no general like him; as a mortal he had a supernatural ability to know where his troops needed to be in order to achieve victory. His strategies and tactics were as close to flawless as was possible from a mere man, even one said to be the son of Zeus.
He won battles when vastly outnumbered. He inspired such loyalty from his men that on those few occasions that he fell in battle, his men actually fought harder in order to get him off the field and then avenge him. At Gaza, when he was grievously wounded by a ballista bolt, his enraged army tore into the city like demons, slaughtering all in their path.
Yet, though he has been known for his brutal and unflinching tactics in battle (let us not forget the atrocities of Tyre), his honourable behaviour surprised a great many in a world where such behaviour was uncommon, especially from kings.
He left competent officials in their posts while weeding out the corrupt, he forced neither religion, culture, nor language on those lands he conquered, and he rewarded those who opposed him valiantly and with honour.
Such leadership, charisma, bravery, and honour made him the ideal choice for The Dragon to make for her emissary. She saw the scale of his vision and realised it matched, perhaps it even exceeded, hers.
She also saved Alexander's life because, following Hephaeston's death, he had been going down a road few return from. A road Alexander trod once again when Jeshua ben Josue died in Jerusalem.