Bon bon, in the Spa the used a rasp for this. But yes, this is more personally. If Lyra really enjoys this, i think even she doesn’t know jet. Maybe this happens to fast for her. Bon Bon for her case means it seriously. I like those two.
I really like this picture! While it displays a lot of emotion, some of it is quite subtle. Lyra is obviously a bit uncomfortable with the situation, but her relaxed face shows that she's content to remain in it. Bon-bon has picked up on her feelings, as evidenced by the hoof she's placed on Lyra's back. It's both commanding and comforting, as if she wants to remind Lyra of the trust she has placed in her.
An images such as this one truly says more than a thousand words about the relationship between these ponies. A remarkable piece.