Chapters 12 & 13

I now know that Forest is being taken over by something both dangerous and mysterious. It is slowly hurting Matty; when will it get to the point that he can't take it anymore? Also, will Matty be allowed back into Forest? Matty has found Kira happy and lighthearted. How will she feel when Matty tells her she must leave her home and follow him back through Forest? Also, will Matty tell Kira about his gift? Will she understand it?