I haven't written much lore for him yet, but i imagine him to be a historian / collector who travels frequently. He learns information from everywhere he goes, Equestria and beyond. He never really settles down for long.
He met sunburst on a journey to the crystal empire. he'd been once before, but that was many, many moons ago.
They're both scholarly types, and i think the exchanging of information would have been the grounds for their eventual relationship.
Even if they don't see each other often, he carries Sunburst's cutie mark with him wherever he goes.
His 'cutie mark' Is meant to abstractly resemble a compass. He's one of those ponies who has a unique navigational talent, he rarely gets lost even in new places.