Quote Originally Posted by Grimoire-M View Post
Apart from that, the minimum requirements appear to be the same as Egi (Know how to Summon, defeated the relevant primal), and it seems we have full control of him from the get go as well, and that along with being temporary we can say are likely features of Demi-summoning in particular.
You don't have to have defeated Bahamut in order to channel or summon him. If I recall correctly the excuse used is that basically everyone in Eorzea got a good soaking of Bahamut tainted aether during the Calamity. He also left his mark on aether streams all across the continent, which can be used as fuel for Bahamut related shenanigans.

Which does raise questions regarding the far east now that I think about it.