Both are absolutely using each other and think they're outsmarting the other.

NOS-4-A2 helps to convert everyone into cybermen because then he can get infinite meals by feeding off them; Mr. Clever wants to integrate everyone into the cybermen hivemind because he is a cyberman, and 'everyone' includes NOS-4-A2 but Mr. Clever's holding off until he's no longer useful unintegrated.

"I'm not programmed to lose!" vs “You can't win!”

They both 'know' how the other uses people, they see it every day! They'd know if they were manipulating them! / They know when the other is trying to manipulate them, but they both let them get away with it because it'll further their own goal in the end.

They're both soooo big for their britches

Like, NOS-4-A2 is initially a subordinate of Zurg & Mr. Clever is 'just' a cyber controller. Usually that wouldn't matter for a cyberman but he's got some personhood about him from being with The Doctor,

They both love and hate it about each other.

Love in that they've each got someone like them and they get to revel in their conquests together.

Hate in that they both think themselves above the other so when one is bragging it just annoys the other one to no end.

They both desperately want to gloat about just how much they've manipulated the other but they're just barely restraining themselves. For now.

They do get opportunities for smaller boasting, which they take as gracefully as you'd expect.

They both get some sick joy watching the other take control of someone.

Like legitimately there is no animosity over "stolen prey" or whatever. Because he's only controlling them for now, they'll be the other's in the end. He can afford to wait.

v desperately trying to find source to link it