To begin with... are they neutered? If not, then doing so will no doubt make life much easier.
Cats have a complex social hierarchy and sometimes they have distressing ways of establishing order. In my experience, as long as they are neutered, you should be able to resolve the issue with patience.
Make sure not to punish or scold Aeon. You will increase the level of hostility and confuse him - remember in the cat world he's not doing anything wrong or abnormal. He's just an alpha male type, not a bad cat in any way.
You will have to let them spend some time together or they will never work it out. Aeon has to make his point and be satisfied and Titus has to feel safe and know that his home isn't threatened. Try to get the point across that you love them both, but that Aeon is not to hurt Titus.
I understand how frustrating and difficult this issue is to deal with and there is, sadly, no quick fix. Just understanding and patience.
I would try petting both cats, and then rubbing your hands with the smell of one cat to another, to transfer the smell of both cats. Then put the cats together and you pet them, to transfer smell of cats to another, plus your scent, as "mother cat". Continue to separate the cats when u are gone, but put them together when u are home, and pet them together, giving them the smell of both cats, plus yours. They should start to realize you are the "mother cat", and work it out.
Otherwise, the two cats will have to fight it out, and establish who is in charge, it won't be pretty, but it will solve the issue. They will fight, but one will become the winner, and the problem will be over. If you don't want to take this final step, then prob best to have someone else own one of the male cats fighting.
Catcaretaker
it's possible that the kitty who got out is so covered in now smells that he no longer has the "pack" smell, you might want to try rubbing each cat down with the same towel, especially scent glands,repeatedly over a couple days to renew the "pack" smell
or it might just be that since the two cats never completely got along, and you are in such a small space, that the more aggressive cat was actually happy he was gone and is now angry that he is back.. to me it sounds like a territory issue.. and the scent thing may help, or it may not.
cats are more solitary animals, and when you put too many in too small a space, they get frustrated, angry, sometimes even hostile..it's like putting two people who hate each other alone in a room for days, weeks, even years.. you can't force them to like each other, and now that the behavior's been started up, it may not stop..
I wish I could give you better news about it,but from what I've read and my own personal experiances..
I do hope it resolves, and I do hope everything works out for the best