Novels where certain characters are really built up before meeting each other, in a ‘met their match’ type of way?

I dont mind too much about genres just so long as its not either romance or comedy. But some kind of thriller perhaps would be ideal

For example, I would have loved it in Game of Thrones ifCersei and Melisandre had met each other… it would no doubt have been immense, but sadly never happened.

So some kind of face-off as epic as that would be great