[Action]
[Sasuke's ears are flat down in annoyance, but they twitch up a little, as if responding to Itachi's. He says, absently:]
There's white on the tips.
[And Sasuke's eyes spin red, and he can see now - Itachi's chakra. Even the ears are radiating a bit of it. What's really bizarre is that it seems to be Itachi's own chakra - it's the same color, even.]