Introducing old stray to young resident cat

Hi everyone, 

Last week I adopted (or rather he adopted me) a male, neutered stray, vet thinks he could be as old as 10, he's been seen by the vet and is now recovering from surgery in a safe room (complete with food, litterbox etc). He is extremely trusting and loving of humans, but I think he's had bad experiences with other cats in his stray days (surgery was required to treat an abscess most likely caused by a bite wound).

Our 2 year old resident - female, also fixed - is a very shy, timid cat but has grown extremely curious about the new cat. This is only day 4, and I know it could be a long process introducing them but I've never tried anything like this and would love some feedback and some inputs on what their behavior means so far, because frankly, our resident cat puzzles me a little.

We've been doing scent swapping with good (neutral) results and have also let the new cat explore the rest of the apartment while resident cat was sleeping in the bedroom (this I do once a day as new cat really enjoys spending time on our enclosed balcony and exploring the apartment). Resident cat has also explored his room while he was somewhere else.

They have had visual contact through a glass door where new cat growled at resident cat and resident cat just looked on and looked a little scared.

Since then they have taken in meals "together" on either side of the door to the safe room 3 times, the door being open so they had visual contact while eating. Resident cat never growls or hisses, just watches and eats, while new cat will ignore resident more and perhaps let out a short growl here and there, otherwise just watch her and eat. Resident cat will throw herself on the floor and roll around when he is watching her. She will even try to get in his room - typically after new cat has finished eating and retreats calmly out of sight. I really didn't anticipate this kind of behavior from resident cat. She will even scratch his door when it's closed afterwards (made new cat growl).

Am I right in assuming this is a good start for these two cats? We have no plans of putting them in the same room any time soon, I desperately want this to succeed!!!! My gut instinct says new cat's distrust of other cats will be the biggest obstacle, and that they will eventually be able to coexist peacefully but as I said I'm a complete newbie. Also, there's a huge age difference in them.

Any input much appreciated!!!

Your doing the right things so far. Having them take their meals between glass more often will also keep good mojo going. Getting each other used to each other's scent is important. So if possible swap out litter boxes so each cat can really smell the other. If possible encourage play from under the door with each cat. When it's time to introduce make sure all nails are cut short even the back ones. Play is aways a good way to introduce but the new cat is a bit old and play may not be high on his list. See if he is a nip head. Try some cat nip to see if it makes him playful. I have 6 cats and other then being quarantined for neutering it was always, "hi kids meet you new brother or sister". The growling and hissing usually subsides after a week but the litter box plays a big part in the actual introduction. Cats nose are not like dogs so best if the cats get to smell the other via the litter box. Good luck.