Yeah he's borderline, I wasn't sure if it was a good idea to include him.

He's silent, but he has always had a face and was emoting with it a bit even in 1993.

Now in the latest two titles he's still silent, and you don't see his face as often, but on the other hand he has started emoting with actions. For example breaking the screen Samual Hayden is using to try and convince him that it was worth the risk to experiment with the hell powers that flooded in.

There is also tons of lore describing his motivations and previous actions. In the end for me that tips the scale towards him being a preexisting character that you play as. But I can also see that one can ignore that and self insert pretty easily.