this is another theory that I have had for a while but haven't done anything with.
I think that in the pits of Hathsin the voice telling Kelsier to survive is actually him being granted a Dawnshard by preservation. my main reason for this is that he describes it as a command in an extremely similar way to when Rysn gets her Dawnshard. another reason I have for this is that preservation says that he was the one telling Kelsier to survive in the pits but the thing is that it is an important aspect of preservation that he cannot speak into the mind of people, only read them. however, the biggest reason I have for this is that throughout era 1 it is a very important thing that Leras couldn't ruin, even to preserve, we know that this isn't an aspect of the power because vin can still do it when she has the shard. what I'm saying is that the reason for Leras being unable to cause harm, even having his hand being forced when he stabs Elend, is that he held a Dawnshard, which prevents him from causing harm. Also who better to hold the Dawnshard of survival than the shard of preservation. now a larger part of my theory is why preservation would give a Dawnshard to Kelsier, I think that the reason for this is that in Leras's grand plan which we hear fuzz speak of in secret history is actually to form harmony and that in order to do that he needed to have Kelsier kill the lord ruler and so needed to give him motivation by saving him from death at Rashek's command, thus allowing the events of the rest of the series to take place, eventually resulting in Sazed becoming harmony. now you may ask if this was preservations plan all along, than why was Fuzz horrified when he found out that Kelsier had caused the lord rulers death. the answer to this is simple in that we hear Fuzz say that he doesn't remember the plan and know that he has progressively lost his mind.
I'd like to know what holes you guys can see in this theory.