Sharee summoned the thing?
-->Yes, in a way, because it reacted to her spellcasting and like a moth to the flame it became drawn to her. That was why it was so obsessed about her,
What was the thing?
-->The thing "was" the covenant of Keldon. The greatest warrior who was chosen many, many centuries ago for his bravery, loyalty and nobility, In the end something changed it, though the presence within Sharee did not know why.
Was the "presence" the same as the thing?
--> No. The Presence was the the Witch of Keldon, an eternal counterpart to the covenant. She is now bound to all those who are part of the covenant. She is your mother, your achilles heel, your everything. If she gets a cold, you all will sneeze. Ohhh: She will not be your only achilles heel. (remember the leaf she tore while she was possessing Sharee).
Are we really privy to this information?
--> Between the prologue and the first chapter a small amount of time pass, maximum two days, and you will dream of past and present, even of the future. Much will be known to you and all this will come to your knowledge. I expect to write a kick arse introduction to the first chapter (and not a journal entry as will be usual) about your transformation and your dreams.
btw: A covenant is a signed agreement (biblical references). I know that Captain. But here it is so much more. It is the manifestation of the agreement. You are the agreement. It will be written and signed on your bodies.
Concerning the covenant, the transformation and your future selves: You will learn much between now and the first entry of Chapter 1, but realize that many of your future powers will be gradually awakening. There will be commandments, laws, contigencies and boosts.
You have been granted a reprieve from the confusion and I hope to make much clear for you, but an essential piece of this campaign will be confusing because deeper layers of the onion exist. Layers you do not know of (but you are welcome to guess. Remember that many, many, many players have yet to enter the stage).