What made Tom Hagen so loyal

Why did Michael fire Tom Hagen as consigliere?

In this film we see MichaelTom firing as consigliere. What happens at the end of The Godfather makes sense when Michael targets an assassination attempt in his own house in The Godfather Part 2.

First we have to consider the meaning of the word "consigliere".

consigliere (kɒnsɪˈljɛːreɪ /) noun noun: consigliere; Plural nouns: consiglieri a member of a mafia family who serves as an advisor to the leader and disputes within the family solves. Source: Merriam Webster

After the attack on Vito Corleone, when Michael, as he learned from his own father, took over the running of the Corleone family, he knew the first thing to do is protect his own family. We see that even among the five families there was never much faith or loyalty that grew in importance after Sonny passed away. Sonny's death by the Barzini family shook the Corleone family to the root. So here Michael wanted a person to fall behind in times of need. He wanted a person not directly related to Michael's direct actions, but someone he could rely on for the safety of his own family. It was none other than Tom Hagen.

Second, it wasn't just Michael's choice:

Michael: If we move there, you will be my right hand. Tom Hagen is no longer a consigliari. He'll be our lawyer in Vegas. This is not a reflection of Tom, it is exactly what I want it to be . Besides, if I ever help who a better consigliari than my father. That's it. [All go except Hagen]

Tom Hagen: Mike, why am I out?
Michael: You are not a wartime consigliari, Tom. With the step we are taking, it could be difficult.
Don Corleone: Tom, I advised Michael.I never thought you'd be a bad consigliari.I thought Santino was a bad don, rest in peace.Michael has all my trust like you.But there are reasons why you don't have to have anything to do with what's going to happen.
Tom Hagen: Maybe I could help.
Michael: You're out, Tom.

Here Don gives us a little hint that bigger designs are in the works, and for family safety Tom Hagen shouldn't have a part in it.

In Godfather Part 2 we find:

Michael tells Tom shortly after the attack, that he is the only one he can trust his family to.

Michael: There's a lot I can't tell you. Tom. And I know that has upset you in the past. They felt it was due to a lack of trust or confidence. But because I admire and love you, I've kept things a secret from you. That's why you're the only one I can trust completely at this moment.

We see he couldn't even trust his own brother Fredo. Here Michael asks Tom to "take over" as Don.

To answer your first question : He could not have done this if Tom Hagen had continued to be directly involved in the actions and steps of Michael. His interactions with the outside world or with other families would have kept Michael from having full confidence in him. That's exactly what happened to Fredo.

For your second question : We saw Michael become very sensitive, hostile, and protective of his family. Since Michael had already started to see Tom as his own brother, sometimes more so than Fredo, he was hurt to find that Tom had withheld things from him.

Michael, after all, embodied the worst of all that his family represented. Even so, he loved his family very much. Family was the most important thing in the world for him.However, he was so vengeful that he would kill his own brother Fredo. He was sane and mad, kind and cruel, powerful and weak. He was a masterful, strategic thinker blinded by vengeance. He would publicly renounce Satan and all his works at the baptism of his godson and promise that he would protect this child from the wickedness of the world while outside his husbands all his enemies would be murdered.

Source: character analysis

Leon

Thank you ... great answer ... lots of information ... @Sudip

M.Mat

The thanks and appreciation were positively rated because of the synonymous importance of courtesy.