Board Thread:Manga/@comment-44086949-20191205133131/@comment-44086949-20191205221716

"we only ended up with Eren interacting with Grisha because Grisha received the memories of Eren from the moment he's visiting Grisha's memories."

Again, you're making the wrong assumption that you constantly recieve future memories. You needed royal blood every time you wanted to use this power. Grisha never got in touch with one after getting his powers, only Eren did.