[hiaux0]

> that made it clear, from the very beginning, that he didn't like me.

How 'directly' was it made it clear?

How is your day to day contact with him?

It is also possible that misunderstandings at the start between you two can spiral out of control (even into hate).

Edit: formatting and spelling

[frustratedmngr]

The area that I manage didn't use to exist in the company, so while I was still building the team (it was my 2nd month into the job) I invited him for a conversation and, before I began speaking, he interrupted me, asked the following question, which derived into the conversation below.

- What have you done so far?

- I am building the team, have already hired X people and they will begin next month. I have also mapped what all other areas are doing and I am planning our deliverables.

- So, essentially, you have done nothing, right?

- Well, there wasn't really much I could do other than that without a team. Besides that, I had to invest some time into planning and showing the executives the structures and resources I will need.

- I got it, you haven't done anything. Listen, I am really close to the the company's CEO and we spoke about you yesterday. I didn't say anything bad about you this time. Besides that, I have a really good relationship with executives X, Y and Z and advisors A, B and C ... [he kept on bragging about himself]

The conversation above really sounded to me that he was threatening me. I spoke with some people in the company I already felt like I could trust about it and no one really understood why he did it.

I ended up thanking him for the feedback and moved on.

EDIT: Added further details that were previously included as a separate comment

[arandr0x]

It looks to me like your hire messed up something about this guy's plans and he set out to minimize damage as fast as possible. Since he had contacts and you didn't, he won (they usually do). Look, when you start at a new place, especially as a manager but even for ICs, it's because someone high up thought they needed an extra person (or a different person). And it's quite likely not everybody agreed with them. It's not really personal (although sometimes these people are OK with the hire but had a dream of a different skillset and don't think yours matches), but it's dangerous.

In those situations you have two options -- find someone he is close to who's more positive about you that you can leverage into brokering a truce, or try to use him for information. (You can straight up ask braggarts what they would do in your place, which usually makes it obvious why they aren't in your place already, in addition to giving you future bones to throw him to keep the hostility in check)

[hiaux0]

Thank you for this detailed answer. On to the next stage:

> I invited him for a conversation

Why was this contact made? What's his connection to your team, ie. how important is his input to your team?

> I spoke with some people in the company I already felt like I could trust

Possible scenario: Chances are that these coworkers are also close to 'that' manager, and talked about it to other coworkers, which eventually resulting into 'that' manager heard that you talked about him. -> Source of hate?

I, myself, would do one of the following options

1. Make your sprint/monthly goals clear to the CEO and at the end deliver

2. Start looking for other opportunities. Since you were well liked in your previous positions, it may be easier to get references.

Hidden option: Look really hard at yourself. Are there unconscious behaviours of you that may cause dislike? Try to apologize to 'that' manager for tiny and unnoteworthy mistakes, he just sounds like a ... who needs more love.