Belarien is a close friend of Prince Tyrion, having been there with him across many battles (and having the scars to prove it).[1a]
Spoilers for Sons of Ellyrion
Atop the Sapphire Gate of Lothern, Belarien would later die defending Phoenix King Finubar from the poisoned blade of a Dark Elf Assassin. Finubar, Korhil and his White Lions had been frozen in ice by sorcery, and though the poison would prove potent enough to kill him a dozen times over, Belarien jumped between his king and the assassin's dagger, taking the blow square in the chest, and in full view of Tyrion.[1b]