This is Nemesis, I finally got the chance to take him in from outside five days ago. He's been coming around almost since I moved in back in February, and would chill on the other side of the door with my indoor cat(s) [one actively chilled, the other didn't care to]. I have him quarantined in a room by himself, and four days ago got him in the a clinic to get neutered, rabies shot, and tested for leukemia. All good to go! Now we can start introductions and trying to integrate. 

So my two cats are five. This kitten was labeled around one. My cats are chill with food, they're not in a rush to eat and will leave their portioned food in the dish as long as they please and eat when it strikes their fancy. Nemesis inhales food as soon as he gets it. Which, understandable, being outdoors definitely leads to food insecurity, and I imagine he'll chill about that someday.

But until he does, I don't know how to integrate him into the house. Like, sure I could feed him in a separate room, but then as soon as I let him out he'll just eat my cats' food. I don't know if my cats will modify their eating behaviors to eat it all at once to stop this from happening. I don't really want them to, because I think taking it slower helps them out, especially with not just vomiting undigested food up. 

Any advice?

New cat has different food habits