I would be grateful for advice on this situation. I'm a senior developer with about 10 years of experience. Until recently my team consisted of myself, my manager, and a staff engineer. We've been working together for about a year. We are all around the same age.
A few months ago we were joined by a new mid level developer. He is bright, clever and confident. He has strong engineering skills and he knows it. He has about 2 years professional experience, and is about 15 years younger than us.
I feel he is trying to assume the dominant position in the team. He behaves like he's the boss. He issues instructions, points out our mistakes, challenges our depth of knowledge.
A couple of specific examples. In a team meeting telling me that it's my turn to run one of our processes, in effect trying to assign me work. Insisting we as a team adopt his preferred continuous integration pipeline, and not taking on board our experience.
My manager and and the staff engineer are gentle people who just seem to go along with it, whereas I feel stressed and threatened. I've been pushing back on this behaviour, refusing to implement changes he wants on my pull requests. I feel like we are heading towards a confrontation.
I'm from the United Kingdom, and this colleague is from the United States. I've not spoken to either my manager or the staff engineer about the problem, as I feel it is at least partly my manager's fault, and that I would be implicitly criticising him.
I would be grateful on how to adjust my or his behaviour so that there is less friction between us.