Second Draft: When Inspiration Doesn't Strike

I've finally figured out a way to tackle my second main character.  As my novel is in the first person and essentially has only two characters, it has been almost impossible to get into the head of the character that ISN'T the first person.  Everything the narrator says or does just bounces off the other character, so everything ends up being a reaction and there's no depth.  I've been troubled by this character since the beginning of the novel - or, at least, since he turned up in the novel (in chapter 12, I think it was)(before that, he was mentioned, so the reader knows he's coming).  I've found it almost impossible to get into his skin.  The fact that he is male has nothing to do with it - more of my stories are told from a male point of view than not, so this was not the issue.  My first draft fell to pieces because I had failed utterly to really understand this character and the 2nd draft has gone the same route - I couldn't figure out the conflict between the two characters, I couldn't figure out his personality, I couldn't understand why the things he did made no sense.  Considering that he's one half of a two-hander novel, this was a serious problem!  I've never had so much trouble developing a character.  My previous novels were action-packed and had many points of view and it was much easier to get inside a character's head when they were very busy doing stuff and doing it with other people.  My two characters in this novel are isolated to the extreme and there is no action at all......except perhaps the sex, which so far is hardly better than porn.
HOWEVER!  I've at last found a way.  I've abandoned my novel for the moment and am concentrating entirely on getting this character's act together.  I tried writing up his past (everything that happens before the novel begins) in a story form, told in first person, but that went awry too.  So I'm doing it my favourite way:

• Using bullets to separate ideas

I'm now onto my third page of bullets and that's just the before-the-novel-starts stuff!  I also managed to work out what drives him, what fuelled his hatred.  Everything I'd come up with was just wishy-washy and inspiration wasn't striking.  One can sit around for days hoping that inspiration will strike in the usual odd place (on the bus, in the bath, before you go to sleep) but as this wasn't happening, I just sat down, every day, to work as usual, and hammered at the point and looked at it from every angle.  It took four days of bashing at air, it seemed, when finally I looked at the mess of notes I had written and realised that, yes, actually, I had done it and there had been no fanfare.  It had been in front of me all along, I just hadn't seen it because I needed to view everything from a different point of view, and the only way to do this was just to make notes and make notes and make notes.  I wrote down the facts and kept writing down the facts until the facts gave the answer:  the character is in pain.  It's pain that drives him.  It's so bloody obvious now that I've worked that out.
I'm now ready to go through every single scene in the book between him and the first person and make notes on what HE is thinking, what HE does between these scenes, what HE knows and she doesn't.  When I'm done, the novel will at last have its sails.