Aeradin was born of Gondor and was raised in a happy household with his sister until one day they were sent to Rohan to the House of Donhelm Greymare. They were 'guests' of Rohan and Master Donhelm Greymare for politics and alliances they did not understand. Donhelm treated them well and raised them as his own but always Aeradin was reminded by the other young men that he was not one of them, he was somehow inferior. This spurred him on all the more so to prove he was their equal or more he was a son of Gondor. Over time this manifested itself as a rivalry with his adopted father Donhelm and later a bitterness developed towards his adopted father.

Coming of age both Aeradin and his sister were released from the pact they had been given into. But instead of them returning to Gondor as was expected the pair headed northward no longer bound to Gondor nor Rohan. Aeradin was now a fully grown man adept in the skills taught to him by his years in Gondor and Rohan. His horsemanship and mounted combat skills like his sisters excelled. It was noted that despite the often harsh words the pair had for one another when together on the battlefield they were a force to be reckoned with. Aeradin would often prefer to be up close in melee whilst his sister kept foes at bay with the use of her bow-mastery.

In time the pair came across an elf by way of chance encounter among the ruins of Eregion. They thought at first he was one of those rangers by his garb until he revealed his true nature. It is not know what was said or how much time they travelled with this eldar, but it was after this time that the Greymare brother and sister were to be seen bearing the clasp of the Warband of Imladris in service to the Hidden Vale upon their shoulders.