Family was everything to the Winchesters.

It was the one absolute they lived by.

Family came first.

Protecting the family was the first priority above all others.

How far had they gone for each other?

What sacrifices had they made without hesitation? Without question?

For family.

To keep each other alive.

Everyone knew it.

Friends and enemies alike.

Knew that there was nothing they would stop at.

There was no question that if anyone in the family were in danger they would fight for them.

Everyone else, strangers, acquaintances, even friends, they were all expendable if necessary.

They would try to protect others of course.

Saving people. Hunting things. The family business.

But when it came down to it, they protected each other first.

For so long family was just Sam and Dean.

The world consisted of two sets of people, them and everyone else.

They protected each other.

They never gave up on each other.

Never did they imagine that anyone would ever get close enough to merit that same loyalty. That same unflinching dedication.

Never did they think a stranger so far removed from them would come to mean so much.

But the day came.

The day when they were faced with a choice.

To stand and fight for someone. Against all reason.

No matter the cost to themselves.

Not because it was the right thing to do.

Not even because there was something to gain.

The day when faced with the question 'why?'

Why fight so hard?

Why risk everything?

The only answer needed came without thinking.

Without doubt.

Because its family.

Because its Cas.