Eygon of Carim Dark Souls III Guide

You meet Eygon in Undead Settlement.

You meet Eygon for the first time in Undead Settlement, while traveling to the cathedral. He is sitting in front of Irina's cell. If you free her (you can either jump down or buy the key from Shrine Handmaid, after you bring her Undertaker's Ashes) Eygon will become your ally.

You can summon him before the battle with Crystal Sage and Dragonslayer Shield.

He appears in Firelink Shrine after the battle with Abyss Watchers (with no further consequences).

Eygon's remains will appear in a cell in Undead Settlement.

Regardless of whether you have summoned Eygon before the battle with Dragonslayer Shield, or not, you find his body in Undead Settlement after you defeat the boss. It is in the cell from which you could free Irina. You can then collect Morne's Greathammer and Howling Shield. Also, you can buy his Morne's set from Shrine Handmaid.

Note: If you give Irina the right book., she can teach you miracles. But if you buy a dark spell from her, Eygon will become hostile towards you. You will find him at the gate, above the bonfire that appears after the battle with Iudex Gundyr. After you kill him, he drops the same items. Talk twice to Irina and she will return to Firelink Shrine.

Note 2: As a result of buying at least one dark spell from Irina, her quest will follow the dark path only.