Welcome to our forum. Dobby is beautiful! The markings aren't very clear, but it's possible he has some bengal in him somewhere.
As for your problem -- it appears you've tried to do things by the book. There is just one problem -- the cats go at their own pace, not ours. Obviously nearly three months should be long enough for the two cats to at least get used to the smells of the other cat. Male cats can be highly territorial -- even at a younger age. There are a couple of things I would recommend:
1. Get some Feliway diffusers and plug them in the rooms the cats inhabit. The Feliway is supposed to have a calming effect. There is also spray that you can use to spray areas like cat beds, etc. It's not cheap, but I have a dispenser in my bedroom and I have only one cat who likes to spray in that room.
2. Try to engage the cats in play together. This means, bring out the wand toys and entice them to enjoy them where their attention is on the toy and not the other cat. From the photo, I see other cat things in the room that should suffice for the two cats.
3. Jackson Galaxy sells Spirit Essences
http://www.spiritessences.com which are holistic remedies for various behavioral situations. Some people swear by them, some think they do not work at all.
Unfortunately, even the BEST of friends (cats) can still fight. It's just like children -- brothers and sisters fight as well. But, you have to get both of yours to where they are accepting and tolerating of each other. Make sure each cat has its own space and area -- this may mean multiple cat trees. Make sure you are spending time on the situation .... putting the cats together and petting them. Giving them treats together.
Most of all, you need patience and you need to give the cats time. Most of them will work things out eventually -- but the time frame is different for each and every cat. When we have members come and post asking whether they should get a second cat -- we usually are hesitant to recommend it. In most cases, things will go well, eventually. But in some cases, it's just not going to happen and you have stressed out cats and stressed out owners. Every cat deserves a peaceful environment where they can thrive and feel confident. Hopefully, there will be no rehoming of any of your kitties. You've got to handle the situation as best you can and make it as easy on the cats as possible to get along.
Hope you will continue to update us on any progress that you make.