(bright music) - I think the relationship with Alphy and Geordie at the beginning was, you know, I mean, after I punched him in the face, that was the first thing that happened.

So it didn't go off to a great start.

But as the season nine progressed, we saw the two of them actually finding that they were a lot more similar than than they thought they were.

They're both working class and they both have a job where they help people and they guide people.

- Even through the investigations, it's the way they relate to one another.

They want to be in each other's company.

And I think that's the root of a good friendship.

- They really enjoy each other's company and I think they are two really good friends.

I think that's their kind of relationship.

Even though obviously, Geordie's a lot older than Alphy, and there's that age gap, they are two equals and they kind of relate to each other in very similar ways.

- Why aren't you grabbing this with both hands?

You clearly like her a lot.

So whenever we're doing a long scene together, I always go, "It's just nice.

Let's just listen to each other as mates," 'cause that's what they are.

- They just get each other.

Geordie, thank you for coming.

- They need each other.

They enjoy each other's company.

And the unspoken thing with Alphy and Geordie is, they love each other, and that's deeply apparent in season 10 when Geordie goes in search of Alphy's kin, his family, his mother.

We might be able to find her.

(Alphy chuckles) - No, we won't.

Well, that is a rabbit hole I don't need to go down.

- It has a profound effect on the relationship and everybody who revolves around that central relationship.

I think I found Alphy's mom.

- We should celebrate you too, for finding your mom.

- Kathy.

Just trying to help.

- How dare you?

I never asked you to do that.

- It's your bloody mother.

- To hell with you, Geordie.

What they fall out over is something really lovely because it is a friend trying to help a friend.

We see that when they have an argument, actually, they both kind of can't stay away from each other for too long.

They both need each other.

I'm so sorry.

- It wasn't my decision to make.

- I shouldn't have said what I said.

(bright music continues) - All in the past.

They've become the genuine engine of the series now.

You care enough about you want to follow and that's what we set out to do, me and Rishi, when we started, get that relationship right and people will follow it.

(bright music)