The sibling war had always been a regular feature of the Smith family before Grandpa returned, and the biggest headache for their mom and dad.
Once Grandpa came back, Grandpa + Morty became the biggest problem.
And successfully turned The Smith Family into The Sanchez Family.
It went from a wholesome family sitcom suitable for all ages straight to HBO-level material.
Which meant that when Morty and Summer started tearing into each other in the middle of the street,
their parents, who used to find this issue such a headache, could now view the two of them with perfect calm.
Like right now...
"Fucking Morty" immediately knew Grandpa intended to send him over to ask what was going on.
As for why Grandpa wasn't going himself,
Morty had actually asked him that before.
The answer was: at my age, just from the memories in my head, I can still build you a black hole generator with my bare hands.
I'm a badass. Not only am I responsible for the team's damage output, I'm also responsible for communicating with outsiders.
Then what the hell is Uncle Morty supposed to do?
Am I, Old Rick, a tour guide whose job is to take you on vacations across the universe?
Fine!
From then on, all those odd jobs fell to Morty.
Official alien social skills, unofficial alien social skills, alien nightclub social skills, alien chicken-shop... Ahem!
Anyway, when it came to reckless socializing, he was your man.
Morty swaggered over and gave them a friendly greeting. The white-robed people exchanged glances, then collectively shook their heads before collectively pointing at Summer.
Realizing those aliens had specifically called for her,
Summer immediately got excited.
*See? This is what it means to be the chosen girl! This is only my third adventure with you guys,