Jack had always scoffed at the idea of opposites attracting. He knew the basics of the science behind the phrase - though he hated to let on that he knew anything sciency - but he just didn't see that it applied reliably to human beings all that often. It certainly didn't seem to work in old cartoons - the cats, dogs, and mice never got along with each other.
In the past Jack had always been attracted to other military-minded people, women who devoted their days to Uncle Sam and their nights to reruns on late night TV. Of course, those relationships had failed because of job assignments and wars and the like, not because of any 'likes repelling likes' nonsense, Jack was quite sure.
Sara was the first aberration from the rule, as she wasn't very keen on the military, and wasn't interested in traveling when his work dictated it. She was content in her job and her city, and she just wanted Jack to come home nights more often than not. He could say that the writing was on the wall because of his job, but if he was being honest with himself, the only thing that killed their relationship was the accident.
It took years, but Jack finally came close to forgiving himself, to allowing another person into his life, and to his great surprise, the person who came to mind was not another military lady, but one Daniel Jackson.
Yes, there were those occasional moments with Carter, where he wondered, but at this point in his life, he didn't want someone who was trying to build a career. Jack had gotten high enough in the Air Force pecking order to enjoy life, and he didn't need rumors and backbiting about an underling sleeping up the ladder, or he himself doing it.
And of all things, Daniel Jackson was the one to worm his way inside Jack's defenses. He still believed that opposites repelled, and hadn't been attracted to a man in years, so Jack didn't think twice about inviting the lost puppy in the hall to come over for a beer their first night back. He never expected it to take so long for Daniel to find his own apartment, or for it to hurt so much the day that the archeologist moved out.
Therefore, it was completely unexpected to Jack when he found himself stopping by Daniel's office on the way home that Friday and dragging the younger man off for drinks and takeout while they watched the game. One Friday turned into a weekly date, which turned into a weekend every time one of them was injured, and eventually a week's vacation every time they had time off after a stressful mission.
The thought of romance didn't really occur to Jack until later, as the beginning had still been filled with hope for Sha're and mourning his son. It wasn't until four years had gone by, and Jack realized that he couldn't imagine his life without Daniel. There had been hints, of course, every time that Daniel apparently died on a mission, but those could have been written off as something else.
It all came to a head when he overheard Sam and Janet (now there was an example of likes attracting) placing bets on when Daniel would just give up the pretense of having his own apartment that Jack began to seriously consider the young man in that light. The ladies' comments didn't upset him, which was slightly surprising, but they also didn't upset Daniel, who was eavesdropping with him at the time.
That was some food for thought for Jack - the idea that Daniel might want to be with him. Jack was used to people pursuing him for his rank and connections, but Daniel didn't need any of that. He had plenty of his own pull within the Stargate program, his job was pretty much guaranteed, and he was the head of his department, with no need to sleep his way higher.
Which could only mean that Daniel wanted to be with Jack just because of who he was, and not what he was. It was a thought that made Jack joke about mental instability and Daniel punch him for putting himself down. It was a thought that kept Jack awake for many nights until he decided to do something about it.
As he helped Daniel move out of his apartment, Jack couldn't help but wonder about the power of likes and opposites. Here was a young, beautiful, intellectual man willing to move in with a grumpy old colonel like him. It was baffling, but then so many things about one Daniel Jackson were, like his constant instance on walking up to strangers off-world, what language he would chose to curse in today, and his amazing ability to survive so often. Perhaps loving Jack was just one more thing to add to the list of Daniel Jackson oddities.
When Jack was promoted and assigned to Washington, he thought that the time had come, that this would be the thing that drove them apart. Daniel would stay with the Stargate program in Colorado - he had to - and they would be split up. Opposite people with opposite goals could not withstand good old fashioned American bureaucracy and time zones.
But Jack hadn't counted on the tenacity of a certain archaeologist-cum-space explorer. Daniel refused to give him up, instead arranging to fly to Washington whenever he had leave. If a few naysayers raised eyebrows, it wasn't any more than the ones who objected to his years of classified work in Colorado. Daniel simply shrugged them off (sometimes literally) and continued to love Jack.
It took years of work in Washington, but eventually "don't ask, don't tell" was repealed. As Sam sat next to an empty seat and cried, Jack and Daniel said their 'I do's' in a small DC courthouse. Jack couldn't explain how or when or why it had happened, but he and Daniel had stopped begin opposites, and just become themselves - Jack and Daniel.