Danny was an ordinary kid from an ordinary family. He was the middle kid of three brothers. It was a pretty idyllic life, with his mom and dad. A very solid working class life. Never too poor, never too rich. His oldest brother, Oscar was the shining star, golden at everything he touched. Adam, the youngest, was the screw up. Constantly getting into all sorts of trouble. That left little to Danny to be special. But that's the lot of middle kids, and well, he loved his brothers and his parents, so he was content.
High school came and went, and he ended up going to community college. A two year degree, mostly so he could say he had one. He did a stint in construction, but with the competition of getting an apprenticeship and the unions, it didn't work out. Somewhere in the middle of all that, he married his high school sweetheart and had a child.
Unfortunately, while he was floundering for a career, his wife was not. She had the four year degree and a good career. The birth of their child barely slowed her down. This led to fights and eventually, divorce. This sent him reeling even more than he had been before. Careening out of control, Oscar pulled him aside and slapped sense into him. Well, mostly. There was still an element of danger involved, when he decided to fulfill one of every kid's dreams by being a fireman.
It turned out he had a talent for it, in as much as one can.
How much of a talent was revealed on Sept. 11th. When the call came about what had happened, particularly with so many of his brothers in arms, he rushed down, prepared to do his part. He's still not sure what or why it happened, figuring after all this time, his desire to 'do something' had something to do with it, but that's when his powers kicked in. Going through the rubble, trying desperately to find some form of life, he began to be able to distinguish bodies from everything else, through heat. At first, he dismissed what he saw as hallucination, as some sort of divine intervention or luck that he managed to find bodies, not always alive, but he was able to see them, even under piles of stone and metal.
But it didn't go away. Even after they returned to their regular duties, Danny realized that he could 'read' the fire - tell where it was burning hottest, where the cool points - possible points of entry - were. And no one else could do this. He was smart enough to figure out that this was something he needed to keep quiet. So he continued to learn what he could on his own, performing experiments on the limits of his power. And he was able to use it to forge a good reputation and career (with that word 'lucky' becoming a nickname).
This strict code of silence came in handy, the day of the Kirby Plaza bomb.
This time his luck had nothing to do with him not being in town, but with his daughter, Sarah. He was her prop for her part on parent careers. For the first time and without any trace of bitterness, Danny was glad his wife had left him, and moved herself and their daughter to Albany. After reassuring Sarah he would stay safe, once again he returned to put his powers to use, saving people and providing aid as he could.
When the news emerged about what had caused the bomb, and remembering the sheer anger and rage and the mood of the city after the Towers towards anyone remotely 'Arab' looking, Danny chose not to register his powers. It was bad enough before in public services when you were gay, imagine if you were discovered to be a mutant - oh, pardon, Evolved? So Danny keeps his head down, he does his job, using his powers when he can and not concerning himself with the rest of it.