Fili stood by them, having to stand by Yavanna, and chuckle along with them. Yavanna was quite the light between the four of them, and the more he spent time with the them, the more of a family came to form between them. He was beginning to finally come into admitting his platonic love for the girl. She was becoming like a sister to him and Kili, and Saeril was filling in that void of motherly affection, just like Dis. 

Saeril chuckled along with them, as soon as she heard Yavanna mention about flying. The result actually left her cape fluttering a little bit, but not transforming.