This story is much beloved by the outright charismatics,
even if does differ fairly widely between the Gospels.
It is presented as a tale of bondage to demons,
which Jesus conquers, commands and expels.
It empowers their magic ministries.
A more realistic view of this tale must see it
as an occasion when gentiles were converted
to the embryo Christian movement.
Jesus had crossed the lake into foreign, gentile, territory.
The number of demons is obviously important to the story,
as is the loss of the pigs over the cliff into the sea,
but perhaps the key word word is "Legion".
This story would seem to involve the Roman armed forces.
Maybe it is an analogy which would be clear to Mark's contemporaries.
Maybe the demon-possessed man implies a collaborator;
someone who has to be constrained from telling all
to the local Roman authorities.
Maybe "Pigs" was a derogatory term used for the soldiers,
whose ability to infiltrate the village has been removed
as they tumble out of the picture.
Perhaps they were those that failed to be converted
and were lost into the wild, untamed, world,
whilst the few were those who changed.
Surely we can see that this is not a literal account.
We need an explanation of the tale which makes sense,
but we no longer understand the coded messages
that those writers embodied in their tales.
We make many strange interpretations,
but they are unlikely to be true!