I'm not sure why a contract would have a sentience of its own.
I can answer that!
Bcs Tiamat is evil b...(how do you call female from a dragon?) and Gith (Githyanki leader who went to negotiate with her) actualy never returned from that meeting ...
There are some wild theories that her consciousness, essence, or being in general is actualy trapped inside the box by Tiamat, as part of her pact made in fact with Vlaakith who wanted to rule instead of Gith but had no legit was to get rid of her.
The only problem with this theory is that in dataminded stuff things that seems to be reffering to the box are reffering to it as a Male ... but Gith was a female. O_o
But that can aswell be just misstake on Larian side.
