Ten line faces at his younger self verbally applauding his chilly voice because it wasn't acting. That was what The Doctor's soul had become and takes a seat next to himself, making sure to block his younger self from his mind. After a moment or two, eyes his younger self still with a line face expression and into those soul-piercing blue eyes. Can you see your own soul, self? How fiery that's become?

The comment from Four before echoes in Ten's mind; So that's why they're brown in regards to Ten's eyes and thinks about ears and leather, The Doctor, Ten had regenerated from. The one who came out of the Time War with gray eyes.