This is from the July 2004 Uncut interview between McCartney and Jon Wilde:

JW: Did you see the Beatles differently from John Lennon?

PM: Hmm. I don't think so. We all had a common vision, at least in the early days. Then everyone seemed to think that we wanted to go in different directions. But I'm not sure even that's true. The thing about me and John is we were different, but
we weren't that different. I think Linda put her finger on it when she said me and John were mirror images of each other. Even down to how we started writing together, facing each other, eyeball to eyeball, exactly like looking in the mirror. That's
how songs like "I Want to Hold Your Hand" were written.

JW: You were like two sides of the same person?

PM: Well said. But the sides would switch. On the surface, I was very easygoing, always accommodating. That came easy to me. That's how I was brought up. But, at certain times, I would very much be the hard man of the duo. At certain moments, I
could bite. But that would be when no one outside the group was watching. John would allow me to take that role because it enabled him to drop his guard and be vulnerable. On the surface, he was this hard, witty guy, always on hand with a cutting
witticism. He appeared caustic, even cruel at times. But really he was very soft. John was very insecure. He carried a lot of that from his upbringing, what with his father leaving when he was five. Then, of course, we'd both lost our mothers, so we
had that in common.

[Snip of elaboration on this theme.]

JW: How competitive were you and John?

PM: There was amazing competition between us and we both thrived on it. In terms of music, you cannot beat a bit of competition. Of course, there's times when it hurts, and it's inevitably going to reach a stage where it's hard to live with. Sooner
or later, it's going to burn itself out. I think that's what happened at the end of the Beatles. But, for those early years, the competition was great. It was a great way for us to keep each other on our toes. I'd write "Yesterday" and John would go
away and write "Norwegian Wood." I'd come up with "Paperback Writer" and John would come back with "I'm Only Sleeping." If he wrote "Strawberry Fields," it was like he'd upped the ante, so I had to come up with something as good as "Penny Lane."

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