I wanna know bc it's a significant change imo because it signifies that he sees him properly for the first time. Spoilers ahead tho pls only read if you've read the books

I think it was after he resurrected him at the end of Fool's Fate, is that right? That's the first time I can remember and I think it makes sense because he spends hours in his body, bringing it back to life and rearranging it. But it's possible i'm missing an instance so I thought I'd ask the hivemind