I summoned Eygon for the dragonslayer fight and before crossing the fog-wall I noticed something weird. He always turns his back on you whenever you look in his direction, even if your character isn't facing his direction. If the camera is looking at him, he'll face opposite of it. It's quite strange, my guess is that I gave Irina de Deep Braile Divine Tome, but didn't buy any dark miracles, so I guess he's pissed at me, but I didn't actually "hurt" her, so he's still allied with me. If that's the truth, then that's some excellent way to convey character without dialog or any backstory. We know he cares about her deep down, but he's not going to show it that easily.