So MIB are a feature of contemporary folklore, usually to be found around UFO sightings. They also feature in The Matrix films as 'agents of the matrix'. I've got similar representatives of a shady organisation in my Castle of Heroes story, but I haven't yet figured out exactly who or what they are. Are they government, are they deep state, are they even human? Patrick, an eleven year old boy, is special. Unbeknownst to him, he's some kind of magical mythical Celtic hero, reborn. Ancient and powerful. His approaching awakening represents a threat to the current order and the powers that be. They want to stop that. He and his guardian are pursued by MIB, from the south of England, up to the Scottish highlands, and then across the sea to Northern Ireland and the eponymous 'Castle of Heroes', where Patrick finally comes into his power. My characters and story are fairly clear to me. What isn't clear is who the bad guys are and why they're so intent on hunting the boy down. Do throw your ideas into the ring. I'd love some input on this. There's a bit more detail in the Workshop: https://www.writingforums.org/threads/the-castle-of-heroes-scene-1-maggie-tells-paddy-his-fortune.161166/
Do your MIB really want to kill the boy or do they actually want to help him, but there's a misunderstanding? Usually with MIB's (not the movie versions) they're thought of as 'bad' or pulling the strings behind the scenes so that events must always go a certain way, or only show up if they need to 'reset' something. The PTB may know that the boy may not be able to control his powers and the results could be catastrophic, but they know the events must unfold safely so they send the MIB after him to show the boy how to safely gain control of his powers, but the boy misunderstands their intent (as per the myths), and flees.
One thing I've always found interesting 'bout the Suits is that you can take it and run whatever direction you want with it. Kingsmen turned them into secret agent badasses, but in the Matrix they're the bad guys. MIB they just keep you from having any idea WTF is actually going on. There are so many options. Maybe your Suits want to capture the boy and control him so that his power doesn't grow beyond control, or maybe they want him dead to prevent him from coming into his power period. Or maybe they're turncoats that haven't had a chance to change clothes. Who knows? Your story, your rules
If you want, you could play on the global secret societies like the illuminati. Or have there be several different societies like this, some hidden, some operating in plain sight, some trying to manipulate the world to their own purpose, some trying to prevent the influence of these groups. You can have fun twisting the conspiracies to meet your world. This also allows for potentially finding allies in the various groups, or have multiple mutually hostile groups chasing him that he can use to his advantage by triggering infighting.
