Curate, connect, and discover
Ever since I saw theories going around about how Prime uploaded a part of himself/his consciousness into Rick's mind when their cybernetics connected I can't stop thinking about it. If anything it's such a good concept for an angsty AU. Prime appears like a ghost to Rick, nobody else can see him nor hear him talk. Rick doesn't know how to get rid of him, he tried digging in his own head, swapping out parts of his cybernetic enhancements, but he can't figure out just HOW Prime did this and it's driving him insane. He tries to ignore him, for his own sanity, but it's impossible.
He sees Prime standing by the window as the family is having dinner. He sees him sitting on the counter of the garage, whistling to himself as Rick tries to busy his mind by tinkering with some new invention. He sees Prime lounging in the back of the ship as he takes Morty on another adventure. As much as he tries to pretend that he's not there, it's all he can think of. Prime is chatty, of course. He wants to strike conversation with Rick all the time, he offers his (very unwanted) opinions on everything Rick is doing, mocks him when things don't go right during his adventures. The family (Morty most of all) would gradually notice that something is wrong with Rick - he keeps staring at empty points in space, glaring and muttering to himself. Sometimes he flinches or jumps at seemingly nothing, and his mood is getting worse by the day.
I'm just so curious about how Rick's and Prime's interactions would go in a scenario like this - they can't hurt each other, they just have to coexist now.