Image imported from derpibooru 
Original Description:
 
Nonbinary child of Spike and Thorax.
 
After reaching maturity, Spike started travelling around Equestria and it’s neighboring lands, meeting some old friends and making new ones. His stay at the Changeling Kingdom got longer and longer however, and at first, he didn’t know why. Then Spike realized he simply enjoyed being with Thorax, helping him rule and protect the lands, or just hanging out. He had always felt strongly connected with Thorax, even in his old form, but now he felt even more of… something! When Ember visited one day, it took her exactly five seconds to figure out what it was. After some convincing, Spike finally proposed to Thorax, who accepted without hesitation.
 
They didn’t think it was possible for a dragon and a changeling to conceive together, so their surprise was great when Thorax found himself expecting one day (I head-canon that all Changelings can carry, as they are monoclinous, aka they have both sexes. They can choose what gender they prefer to be called when they are young, if any). Laying was safe and painless, and in few days Petiole hatched. Greatly loved by both of their dads, they grew up in a safe environment, though greatly sheltered in progress. They don’t have many friends due to their shyness. They are sort of an blank page still, as they don’t have much in sense of word experience.
 
Petiole can breathe fire like Spike, and has normal transformation-powers of a changeling.