Learn English – What’s the pro and cons of using “though” at beginning and at the end of a sentence

Small children have a particular writing style that teachers often mark as wrong.

We had a field trip. And we went to the zoo. And we saw monkeys. And they were funny. And then we went home. And the bus was noisy.

Nobody thinks that's a well-written story. So the teacher circles all the "And"s and says "don't start a sentence with and". But somehow we all internalize that as a rule for all of life — which it isn't.

Grammatically, though is not the "right option" for the sentence because though is commonly used in a subordinate clause (Though I am hungry, I will not stop for lunch), in a participial phrase (Though bored beyond belief, Jonah continued reading), or as an adverb (Yeah, it was an impressive movie. A bit long, though).

A writer might take liberties and use though in the way that you have (a subordinate clause separated from its main clause by a period) for effect, especially with a long main clause and an impactful subordinate clause (Every morning from then on she would set out from her cabin at dawn to wander through the forest, enjoying the smell of pine and the sweet relief of solitude. Though she never completely forgot Ted.). This is not as common as using coordinating conjunctions in this way (and, but, or...), as you've done at the beginning of your passage. But it is not unheard of.

Alternative words might include: however, still, yet, and other concession words. Still, the preceding sentence tells us that she would "follow us whenever we went", which I presume should be "wherever". For this reason, writing that she "spent most of her time sitting on the wooden steps" seems contradictory, unless the "we" rarely went anywhere.