Isabel, maybe you could argue is just a deliberately ignorant mob wife. But the others are violent criminals holding him hostage. Trusting or even having a mild liking for any of them would be the definition of insanity.
The reason I said he has legitimate reason to trust them, is because they exposed massive vulnerabilities to him.
Luna & Isabel have both confided in him with huge personal issues.
Gracie, to a lesser degree. But she's let him in.
Trust enables trust.
None of them had anything to do with MC being taken, nor did Joey, nor did Serpent.
Of the people he's met, only Cordia, Antonio & Wilfred (+Blackie) are even aware of his contract, most people have no idea why the MC is staying in the main house, with the Family.
None of them has been violent to the MC.
Sure, there's been violence in his presence, but that has been against other people, trying to kill us. Justifiable.
Even if MC
was being held captive, people can enjoy the company of their captors, it's quite common.
Have you heard of Stockholm syndrome?
I see your point. I don't agree with your reading (I think it breezes past the basic premise that these fuckers are holding the MC against his will and their talking of him as "family" or "theirs" is wildly insulting), but I can see how it makes sense from your point of view.
You're assuming it's against his will, but when has he expressed any desire to leave?
He was taken without him knowing why, but that doesn't mean it's against his will.
It's not as if he was locked up in the boot of the car, he was freely (willingly?) sitting beside Wilfred.
If it was against his will, he'd have tried to leave, long ago.
The only "will" he's expressed is to investigate the situation, not to leave it behind.
His Mother (& presumably his Father) are\were criminals. So is his childhood friend's whole family.
These are the type of people he's grown up knowing, in that context I really don't see why you find his acceptance of them so strange.
He reads people exceptionally well, so he's judging them for "who" they are, not "what" they are.