Not much is known about Julian's history before the party met him during the events of the Feywilde Ball. Valanthe introduced him as the Caellond steward for the Feywilde side of the crossover, but the party didn't get the chance to speak to him at much length. He greeted them at the start of the party, and was present during the feast (though he didn't speak much, deferring the conversation to Magdiel), and the party encountered him briefly before talking to the King of the Forest, and finally again when the ball was ending.
He was comically a victim of the Acorns and Stones during the feast, reacting pretty strongly to the foul taste of the rainbow mouth effect. Aside from that, however, he mostly kept quiet and in the background.