Gray

Gray is a Hero in Xenoblade Chronicles 3.

Hero Quest
In the Hero Quest A Gray Matter, he demands the party to hand over a piece of an unknown metal (unknown at the time, an Origin Shard) found on Murmur Rise at Millick Meadows before attacking them, only for him to retreat by diving into a lake with the arrival of Kevesi troops from Colony 23. The troopers asks the party where he is before realizing that they're Ouroboros and attacked them, but were forced to retreat. After the scuffle, the party decides to track down Gray after they deem him an ally. They follow his footprints to the end pf the river bank.

Once they caught up with him, Gray was surprised that the party manage to track him down to deliver the metal to him, before identifying the party as Ouroboros, much to the party's shock. Lanz and Eunie then accused him of attacking him out of the blue because of the metal, with Gray claiming it was a warning, before Gray warns the party that they were followed by the same Kevesi soldiers that attacked them before, this time bringing two Sagittarius-type Levnises. Eunie then accuses Gray of bringing the soldiers to them before he claims that the blunder was on the party's part, not his. Regardless, Gray decides to assist the party in defeating the Kevesi soldiers.

After routing the soldiers, Gray lets the party keep the metal before joining the party as a Hero, trusting his deceased friend's words before claiming his attack on the party earlier was a test as a request from his friend.

Other appearances
Once the party reaches the City, Gray can be found there as an NPC.

Gray can be among the recruited Heroes to aid the party in the final battle against Z, stating that this is his last mission as he is summoned. After Z's defeat, Gray can be seen with the rest of the Lost Numbers as Aionios splits back into the two worlds it was created from.

As a boss

 * Mystery Man