I know Clara gave herself a little “wiggle room” before facing the raven, but I really don’t think Clara would travel that long. Travel a lot, yes. Perhaps even obsessively so. But not for centuries as some posit. She’s way too much of a control freak to… “allow” herself such unfettered time that she feels she does not deserve. She would restrict it for herself somehow. Infinity made finite through choice. I would wager that she gives herself the same amount of time in years as what she would have had with an average human lifespan. Being able to see the universe for that long, eternally in her prime , that alone is more than what anyone else gets, more than what most companions get even.Certainly not with their own TARDIS. So I’d imagine that that’s what she’d allow herself to take from the Doctor’s bargain with the universe.
If anything, she might go even less. She might choose the remainder of her mother’s average lifespan, what it might have been, should have been. Her unlived days , calling back to why she wanted to explore the world and later, the universe to begin with. Given how young her mother was, quantitatively doesn’t make much of a difference, but it gives a completely different lilt to her character arc , looping it back around to the beginning of Clara Oswald herself.
Or perhaps, the romantic in her would win out. Perhaps she’d affix her “lifespan” to something seemingly arbitrary. A tree on a distant planet that has lived for millions of years and is nearing the end of its life perhaps. The day it loses its last leaf, is when Clara Oswald , the girl who blew into this world on a leaf herself, decides it’s time. She might even choose that singular event to be …the Doctor’s regeneration. Her Doctor. The one that saved her to begin with. The one she watched be born , who dropped his veil for her. Yes, future Doctors might very easily cross timestreams while 12 is still kicking around, but from the chronological reference point of Earth, the day that the Doctor that starts sauntering up, is someone else, someone new, the day her Doctor has found a way to move on is the trigger for her to do the same. Till metaphorical and literal death do us part and all that.
Which option would you favour ?
Average human lifespan (from her age)
Average human lifespan ( from her mother’s age)
Some event, arbitrary/astronomical that she singles out
12’s regeneration
She lives until it just …feels right or she begins to get apathetic to it all
Other option ( do tell !)












