To say Rick Sanchez has a complicated life would be an understatement. On the surface, Rick is a cantankerous old scientist and possibly the smartest human being on Earth. He's able to invent and craft - both useful and meaningless - with ease, travel through time and space like it's nothing, and survive countless dangers. Nothing seems to tie him down, allowing him free rein throughout the multiverse to pursue whatever madness he feels like getting into that day.
Rick is a crude man who has little morals for the things he does. He walked out on his daughter Beth and his then wife, only to arrive years later for unknown reasons. He belittles his son-in-law and drags his grandson, Morty, into traumatic situations without any concern for his safety. He considers mundane, everyday needs like school and love to be utterly pointless. He wanders into interdimensional portals and exotic alien planets, only to leave them worse off than before (intentional or not.) Rick heavily distrusts the government and at one point, actively fought them. Everyone he meets, including alternate counterparts of himself, are not spared from his apathy and biting sarcasm. Rick has seen and done far worse than the average human for seemingly no purpose. No matter how much his family chews him out on this, it isn't enough to deter him. He comes and goes as he pleases, following his own defined code.
Internally, Rick's drunkard behavior is but a facade. He didn't get far into his life without hiding a few skeletons. Rick is deeply depressed on the inside, numbing his pain through booze, drugs, and death-seeking adventures. There are hints he's guilty for the pain he has caused, so he excuses his addiction and bluntness to push his family away. His past is shrouded in mystery, left unrevealed as Rick does not wish to dwell on further grievances. His boorish attitude is a cover for the help he desperately wants, but there are days when he wishes he could just end it all.
A fortunate silver lining exists the more he spends time with The Smiths. Rick is fiercely protective of his family when he senses something genuinely upsetting them. Despite dragging his grandson against his will and exposing him to deadly situations no child should go through, Rick will go out of his way to shield Morty from outside threats or sincerely cheer him up when the kid is down. In return, Morty serves as his moral guidance. Rick cares more than he wants to admit, but that may be what saves him in the end.