Cats are like people, some seek out attention while others are perfectly happy to be alone.
 It is hard to tell what your cat had been through up until you guys gave him a forever home. Being I'll at first didn't help & now that he is feeling better he is just taking his time getting used to his new normal.
 Have patience...just give him space & let him know you care by giving him a special treat when he seeks your attention or maybe one a week etc.
 Once he decides that you are forever he will probably settle in but it will be on his terms. 
 I wish you the best!

Cats are like people, some seek out attention while others are perfectly happy to be alone.

It is hard to tell what your cat had been through up until you guys gave him a forever home. Being I'll at first didn't help & now that he is feeling better he is just taking his time getting used to his new normal.

Have patience...just give him space & let him know you care by giving him a special treat when he seeks your attention or maybe one a week etc.

Once he decides that you are forever he will probably settle in but it will be on his terms.

I wish you the best!