Gibbs/Fornell so married to each other and so "old settled couple."

Tim/Tony on their way to becoming the same.

Maybe Gibbs is an immortal in the same way as that guy in Highlander the tv show.

I'm tempted to write "missing scene" fic where Gibbs and Tim work out between them that he should stay close when they find his door unlocked to be "backup" just in case.

That and "after episode" fic where Tony acts on his desire to see Tim naked.