Idioms:

walk all over sb
to treat (someone) badly and without respect
If you don't want to work at the weekend, say so - don't let the boss walk all over you.
• Greg lets his older sister walk all over him
You shouldn't let him walk all over you like that.
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lose your grip
to lose your ability to control or deal with a situation
He was losing his grip at work and knew it was time to retire.
It suggests that the ruling party is losing its grip on the middle classes in some of the bigger cities. [often + on]
• Unfortunately, lately her mother seems to have lost her grip on reality
get/keep a grip on yourself
to make an effort to control your emotions and behave more calmly:
I just think he ought to get a grip on himself - he's behaving like a child.
loosen your grip
If you loosen your grip on an object, or your grip loosens, you hold something less tightly:
He held my hand very tightly at first but gradually his grip loosened. loosen your grip/hold
If you loosen your grip/hold on a situation, or your grip/hold loosens, you decide to control it less:
The dictator's grip on the country has not loosened.
relax your grip/hold
to start to control something less:
The Mafia has relaxed its grip on local businesses.
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pull yourself together (CALM) phrasal verb [R]
to become calm and behave normally again after being angry or upset: If you pull yourself together, you behave in a less emotional way and take control of what you are doing.
Just pull yourself together. There's no point crying about it.
Pull yourself together, now. There's no point in crying. [often an order]
• Bobby had to pull himself up out of the hole.
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Pulling The string
pull the strings

to be in control of an organization, often secretly
I'd really like to know who's pulling the strings in that organization, because it's not the elected committee.
I want to know who's pulling the strings around here.
Who is really pulling the strings at the White House?
pull strings
to secretly use the influence you have over important people in order to get something or to help someone: To pull strings is to use important or influential people to help you achieve something:
Wilson is a very important man who can pull strings from a long distance.
I may be able to pull a few strings if you need the document urgently.
Samuels pulled strings to get her daughter a job in Mitchell's office.
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Call the tune
call the shots (ALSO call the tune)
to be in the position of being able to make the decisions which will influence a situation
Here, democracy does not really exists. The generals call the shots.
He who pays the piper calls the tune. SAYING
said to emphasize that the person who is paying someone to do something can decide how it should be done

something that you say which means that the person who provides the money for something can decide how it should be done
You may not agree with Mr Brown but he funded this venture, and he who pays the piper calls the tune.
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To twist somebody round your little finger
twist sb around/round your little finger
to be able to persuade someone to do anything you want, usually because they like you so much:
He'd do anything for you. You've got him twisted around your little finger.
He'd do anything you asked him to. You've got him wrapped around your little finger!