I love how Downey discusses Holmes and Watson's relationship. First he jokes about their "circumstantial homosexuality," then he says:
We kept talking about getting into the spirit of 'What does it mean when two people are so close they almost can't stand each other, but they can't stand on their own without each other?'
It means love of course. Whether you believe it is merely platonic friendship or passionate romance, it is certainly a deep and lasting love.