Do you ask this to know if he's a real guy or an AI or a pseudo for group of persons like https://en.wikipedia.org/wiki/Nicolas_Bourbaki ?
I know Fabrice a little. He's definitely real, smart and humble.
Visited him at his workplace about ten years ago when he worked at Netgem.
We also have a common friend we visit with spouse and kids, where we discover and discuss new gadgets (physics-based, drones, mechanical puzzles, etc). One day we played with a kind of padlock where the lock procedure implied to move a sort-of 4-direction joystick. The trick was: you could do any number of moves to lock it. It seemed like it allowed to store an arbitrary long sequence of numbers in a finite mechanical system. Fabrice arrived, heard us explain, thought, and said "the mechanics probably implements some sort of hash algorithm". That was the answer.
He is definitely very humble and a very good listener. When he told us about this side project he was working on about a year ago, he made it seem like it wasn't a big deal, just a small js engine, would never compete with v8. After a few questions, it was clear that the goal was to implement the latest ECMAScript spec, with all the goodies. It will never be in the v8 league, but it's on a league of its own.
With how things are going now, V8 code is the de-facto "upstream spec"