ARC 1: Dissociate
So I kick back, and I dissociate.
Around late 2019, Raiden is suddenly kicked out by Rose, handed his belongings and told to never return. Distraught, as he notices a gap in his memory to understand why she chose to end their relationship so suddenly, he returns to the US and Maverick's Headquarters in Nevada because he has nowhere else to go; running out of money because he's bad with that, and completely out of options, because he's also bad with that.
Raiden has been straight up ruining his life with the decisions he made in the past and now all these consequences are right thrown into his face. He has reached the edge of society with seemingly no way to return, having cut all ties with everyone — and now his family, the last people he seemed to have a connection to, is gone as well.
But he's not even sure of everything, considering that his memory keeps giving out, again and again and again, finding himself in situations he didn't remember how he got into them — covered in dirt and blood, or reeking of alcohol, or finding himself in the possession of things he should not even own in the first place.
At Maverick, he is not received with the same reception he has hoped for, but they don't kick him out either. Better than nothing when you got nothing in the first place.
He is presented with the fact, however, that Sam survived and has now taken his place at the PMC.
It confuses and irritates the hell out of him, especially that Sam seeks his company and wants to 'make up', that Raiden cannot even begin to fathom.
He rejects Sam, and Sam seems deeply hurt by that.
Not to mention that Sam seems like a different person. They gave him different armour that is completely white, no longer bearing Desperado's logo nor that same metal arm. The new one is of a similar design to his combat form, so it was clearly designed by Doktor. More punches in Raiden's gut.
Unlike his former teammates and his family, Sam receives him positively.
While everyone else seemingly rejects Raiden, Sam wants to be around him, what seems to be almost something like desperation. So Raiden gives him a chance to talk and make 'friends'.
Maverick asks him how “fighting his own war" is going, and Raiden cannot tell them much, other than that he makes sure to deal with what's left of Desperado that somehow still is active despite him ending its sponsor and leadership. Sam asks to go with him, but Raiden tells him he won't need his help since he does not trust him at all.
Just a few days later he is asked by Kevin to sign an NDA about Sam, and it makes him so suspicious of everyone and everything. Who can he really trust, if he cannot even trust his former employer and teammates? Why is Sam out of all people suddenly the only person who tells him the truth?