The tom that keeps coming back

Ezzabella seems settled and content staying inside. However I'm a bit concerned about the tom cat on the outside. Since last summer I would get an occasional visit from a calico cat. One day I approached it on my back deck. The cat was rather muscular, and by it's face it looked a little weathered and worn. It was calm and friendly, it allowed me to pat it, so I put some dry cat food down for it. Much to my surprise it refused the food. First thing I thought was this is someones pet, and it looks like an old tom. Another day it was clawing at my front screen door. With Zelda safely locked in the back room, out of curiosity I let the cat in and offered it some dry cat food. I feel if a cat is starving it's not likely to refuse any food you might offer, but once again he refused it. He had his nose up and sniffing as he strutted around the house checking every nook and cranny out. Then he returned to the door asking to go out. A few days later I viewed him sniffing around the back deck, and spraying the leg of a chair. After witnessing that performance, I concluded he was a tom, and he was not not neutered. My worst nightmare is what if his ongoing visits are in search of Ezzabella?

  His markings are similar to this, with a little less spots on the top of the head and back.

Very much like this, only his face is wider, his eyes rounder and a bit puffy. In-spite of being friendly to me, he looked like he has seen a few battles in his day.  One day last summer I opened my door to discover him standing on my front deck.  Zelda was standing on the steps looking at him as if to say "get off my steps you intruder!"  As I slowly opened the door he seemed calm, so I called Zelda in. As he watched, she carefully walked by him. When she got almost in the door, she acted like a yowling  lion. He jumped back with his ears pinned back, almost in shock, as if to say "well geeeze what's your problem?!"

Yesterday When I went through the daily ritual of opening the window to see if Ezzabella wanted to go out, she once again refused to even go near the window. There is a lot of fresh untrodden snow out there, so the first thing I noticed was paw prints on the top of the wooden box I set up so Ezzabella could come in. As I looked around I also noticed paw prints through the deep snow coming up to the window. Seems this tom would only be persistent to be with this cat if it was in heat. And if Ezzabella was in heat, wouldn't she be acting strange and insist on going outside? Other then searching for food and a suitable mate, why would this tom keep coming back? I'm wondering if cats (other then mating when in heat) form friendships with each other?  I have seen him come through my back yard, trucking through the deep snow, with only the top of his head and tail in view.  Gosh I hope Ezzabella is not pregnant?