Xi knew Shiro, Sam Holt, and Matt Holt when Zarkon's Forces imprisoned them, though he never learned their names. After Shiro and Pidge saved him from Sendak's warship, he and his friends were brought to heal at Allura's Castle of Lions. There, he told the two of them how Shiro was a legendary gladiator who won against the infamous Galra Gladiator, Myzax, and earned the name "Champion". Afterwards, they returned to their families.
Xi respects Shiro with equal parts awe and terror, having seen Shiro's unbridled ferocity in the arena first-hand.