Loda deserves flak for a lot of stuff.
But it is very reasonable to assume he had planned out the major aspects of one of the two main endgame villains.
"It isn't he, it is them"
The straightforward implication here should be Luffy/Zoro talking about multiple people present within Blackbeard, cause it's just weird to refer to crewmates by "it isn't he but them". Makes no sense.
Yes, it's weird that they get surprised by leopards and shit when they were just straight up serious here without shock. But they were straight up serious regardless, and the "them" was emphasized by Oda.
And then there is Blackbeard being able to eat a 2nd DF. We know a single person can only eat one DF and a 2nd DF kills him. A straight forward explanation to BB being able to eat 2nd DF, was the presence of another soul/person within BB having the 2nd DF. Either that, or some unprecedented exception.
Then there is Blackbeard switching up his personality all the time.
One is a coward, one is a giga darer. I always speculated that the default Blackbeard is a coward, while the conqueror is another soul that takes over when the opportunity presents itself.
Then there is Blackbeard's Jolly Roger having three heads.
Oda has been very consistent in dropping these hints pointing towards one direction.