I will go with my paternal grandmother because she basically raised me. I'm a product of Catholic sex education in the late 70s/early 80s (soo no sex ed for my parents, basically). My mom got pregnant while my dad was in college and was essentially kicked out of her house. My grandmother took her in and my parents were married 7 months before I was born. (Or maybe I was a 9.5lb premie as I was originally told ;P).
Anyway. She was both a bitch and a badass. Good luck to you if you were on her bad side. Really. Good luck. But if you were on her list of good people, she would give you anything you needed.
She was a blonde-haired, blue-eyed fiery Colombian woman. So when my mother gave birth to the (only) fair-complexioned child, it was pretty obvious that I would be the favorite. (Latinos and skin color are an interesting dynamic - another discussion for another time.)
She basically raised me as my parents worked and we lived in a house together. She used to take me for long walks with my stroller full of my dolls. On her way home, my mom would run into us and drive us all home.
We got into a lot of weird shenanigans. Like dicking around on my mom's stairnaster and breaking it. We then managed to buy the replacement part, fix it but it never really worked the same. It was a secret we both let out on her deathbed.
She was strong as hell. There was a time where a trunk that weighed at least 100lbs made it from the floor to on top of a bureau. No one knew how it got up there but then she was like "oh no, I did it" - so some sort of deadlift into a powerclean.. I don't know. But she was in her 80s at this point. (In retrospect, she had the PERFECT powerlifting body... sigh.)
In her 80s the dog started getting really attached to her. Turns out it was ovarian cancer and the dog knew before anyone. It took her in a few years but this lady was literally a MACHINE up until like a few months before her death.
Not disappointing my grandmother is what kept me out of trouble as a kid. I could give two shits about what my parents thought if they found out I was messing around but Abuelita? SHIT. She was not someone to get upset.