She drinks wine, because she daren't drink the water. The water is dirty here, and the unsanitary conditions have probably contributed to Susan's sickness.
Barbara has never liked wine all that much. She's not much of a drinker, although she has been known to take a pint with friends on weekends.
But this is not England and she is not among friends. She's got to take charge, be strong, stay healthy.
The Doctor is gone.
Ian is gone.
All they have is the kindness of strangers.
She'd laugh if she weren't so tired.
He eats because he's hungry, because he must keep up his strength. He thinks of meals he's eaten and forgotten, moderately priced luncheons at typical British pubs, fish and roast and chips and good strong beer.
He eats this because there is nothing else to eat, and he must stay alive.
Barbara and Susan, marched to the guillotine.
The Doctor, lost in a burning country house.
Sense tells him there is nothing to live for, that the only people he cares about are dead, have never been born, and there is no way to return to the time and place he belongs.
But sense is not the ruler of a man's body. Hunger is, and Ian eats.
She sleeps, in fits and starts, hot skin and terrible dreams joining forces against peace and comfort.
Is the heat from a fever, or the flames that consumed the house where her Grandfather was lost?
She sleeps, because her body cannot bear anymore strain, her mind cannot bear anymore fear, and her heart cannot break one more time.
She sleeps, because after all is told, Gallifreyans are not nearly so hardy as the humans she travels with.
He plots and schemes and cajoles. Steals one coin to use as a lure, another to bait the hook, both coins stolen from the same man, both coins left at the scene of the crime as he makes his escape.
He plots, because that is what he does, and that is how he copes.
He schemes, because scheming keeps him from worrying, and a Time Lord is not supposed to worry. Not about silly things like life and death. No, Time Lords are supposed to be above the petty concerns of mere mortals.
Like his granddaughter.
Like young Chesterton and brave Barbara.
Like history being more dangerous, more brutal, and more overwhelming than he'd ever thought.
He could return to his TARDIS, return to his travels, leave them behind to fend for themselves. Even Susan. She's almost grown now. Mustn't hold on to the apron strings forever, mmm?
But he can't, because his hearts cajole, and his mind schemes, and his voice plots an escape even as his feet take him down the road to Paris, and more danger than he ever wanted to face.