Which Character was the "Glue" that Held the DS Together?

Trask.

....but also, so much of DS is Laura/Angelique (different...but the same).

Early 'scary' stuff...Laura.

Later scary stuff...Barn (but then we find out, that's from Angelique).

Then comes Cassandra....

Then we see witchy Angelique in 1897.

...and we also see Laura in 1897!!

Every time after 1897, when it's 'supernatural', someone (usually Barn) finds a way to seek Angelique's help.

....more glue....

Patti

Nicholas Blair, Evan Hanley, Charles Dawson. Those 3 characters r the glue of dark shadows.

Evan Hanley

No character was the glue, because the glue was Collinwood.  The house, not the estate.

Jeb Hawkes, obviously. He left the stickiest footprints.

Glue? Well, I could sit and contemplate on who would be a glue character to hold DS but I tend to think of it this way...
     More like gears, the gears inside a clock perhaps? Sounds good? Because gears must work together to work and keep the motion going (in this case, work to keep time going.) If one gear is misplaced the whole working chain just...stops. To me, each character was in turn holding another character in his/her place and kept DS going, just like a clock. 

I don't know which character was the glue; however, I can think of several who were the sandpaper that grated on my nerves. 

No character was the glue, because the glue was Collinwood.  The house, not the estate.

As you say this I think that you are right. It was Collinwood that everything was centered around. And to the lesser degreee The Old House.

I think that DS was held together with actual glue.   

I think that DS was held together with actual glue.

Actual CRAZY glue, maybe......

Julia and the contents of her little black medical bag...nuff said. 

Keeping David and/or Quentin alive was the glue that held it together. But, Barnabas was the main man in my opinion.  If either David or Quentin had been killed off, Barnabas would have latched on to another unfortunate one to help (or hinder).