Below, on the left, is the kitten I found across the street from our house about a month ago, and Buddy, our big ol' gray cat. Buddy is appropriately named, as he's very friendly. Since the new arrival, Buddy and the kitten have become fast friends: tussling, chasing each other around, and sitting together a lot. Our grumpy oldest cat, Muffin (not pictured), doesn't bother much with the new kitten, but then she's never bothered much with Buddy, either.
With the new friendship in force, we don't feel quite as bad leaving the kitten home alone during the day when we go to work, as Buddy keeps him occupied. It's all working out.
Now, if we can finally, finally settle on a name for the new cat. We're thinking Midnight, because it was around midnight when I took him in that night back in November. We'll see.