The Decepticons do NOT want to give you up.
Why would they?
You fulfill something for each of them in your own way.
The vehicons love how much you care about them, patching up any wounds and entertaining their gossip. Being heard and listened to builds their confidence and work skyrockets. Most times, you'll be with a group of vehicons doing whatever in the moment.
Given your bigger size, you were able to help Knockout clean and buff himself much faster, and he had a gossip buddy who actually indulged in his possible ideas. It certainly helped when there were too many patients for him to deal with on his own.
Breakdown came around at a certain point, rumored because you helped patch him up after the whole Sylus debacle. He likes being held in your arms and ranting to you, much to his embarrassment, but it's usually in the his room so it's fine.
Soundwave... No one is really sure what he likes about you, given many don't know much about him personal wise, but the fact you're allowed to carry him places and talk to him WITHOUT being pushed away, speaks volumes.
Starscream showed great disdain for you at first, but with a few compliments here and there, he eventually melted. When others are around, he shows a rather pompous attitude, but secretly(not really a secret when everybody knows...) tries to show off for you.
And it doesn't go unnoticed.
Megatron sees how the vehicons and Starscream like making you proud, how Knockout and Breakdown listen to you, Soundwave seems to do more WHEN listening to you(which confuses him???)
Yet you don't ask for anything. Humans usually fear what they don't know, so why don't you cower?
"You work with us without asking for your freedom. There must be something you want after all of...this."
Seeing you hold a vehicon, who's most likely shitting themselves at him suddenly making an appearance-
He CANNOT take you seriously. Now he knows for certain you won't be any trouble.
"I don't know, just keep me fed and entertained and I'll do whatever you need of me."
"...That can be arranged. Soundwave will assist in whatever you need."
"Cool."
Megatron still doesn't get the hype for this fleshy creature who seems to not know danger, but why ruin something that helps him?
That would be rather dumb.
So when the Autobots find out about you being aboard the Nemesis, your place with them is being threatened.
As if they'd let their lovely future partner servant be snatched away!
This is the first time the Autobots have ever seen the Decepticons fight together so well, and it's giving them a hard time-
Meanwhile, you're on the ship with Soundwave playing chess, blissfully ignorant to the battle outside.