Mowgli learned to emulate many animals trying to find his true identity, until he met Kaa to discover who he really was... a python! XD
So, from many lengthy convos with Bagheera, Kaa found out that hoomans can be made bendy like snakes and since Bagheera was in a harem before he ran off to the jungle, he often saw dancers holding postures that exceeded the panther's own cat-like flexibility in so many ways!
Kaa was more than surprised to consider he might have something in common with humans but as an old wise python he wanted live proof so he'd often wisely stretch and hold the young man-cub for a while which Mowgli saw as part of their usual struggle without even realizing his body's indeed slowly getting to the point where he can precisely replicate python's coils.
"Told you", Bagheera grinned. The wise python nodded and officially proclaimed Mowgli a snake brother, which in turn opened the door to learning many things that Kaa reserved for his snake students only... <3
I always wanted to mix human and snake flexibility somehow in one picture and seems like I finally found the right characters for this idea! :D By the way, this fanart is NOT based on Walt Disney's interpretation but on the original book by Rudyard Kipling.
Also, I foresee questions about Mowgli's added loincloth here, well, that place in the book was edited later but in the first edition beside The King's Ankus, Mowgli also finds The Queen's Panties *giggle* <3