In a relationship, D/s or otherwise, who is responsible when it comes to trust?

Both parties are responsible to do their part in being trust-worthy and being able to trust

Does trust need to be earned, or is it something that should be freely given?

To me, trust Must be earned - there is an olive branch of it offered, in hopes they will be but true, full trust from me isn't given until I know they can accept it responsibly

If there is mistrust, who is at fault? The person who has the feelings of doubt, or the one is isn't being trusted?

Again both sides are - One side in not clearing any thoughts that have led to the mis-trust and the other side in not being responsible enough to show there are no reasons to mistrust

What if there aren't any reasons to be mistrustful, but it is just a result of insecurity? How is this best dealt with?

To me all things belong on both sides simply (in almost all things, trust included as it is not a one-sided thing) - one side tries to work on their insecurity by communicating it and the other side tries to understand and help with communication and patience. What happens when blind trust is provided, but undeserved?

Is it enough to just say "trust me?"

That statement would only hold true for me if I had already agreed to put my full trust with them, then questioning after the fact is a bit of a lie on my part in that I commited to something I didn't mean Blind trust however, is a hard earned thing for me but truly once given, it's implicit. If it is underserved, it will rear it's ugly head soon enough and will hurt the person deeply but unfortunately that's just part of life and the scum in it.

More specific to a D/s context, what if a Dom states that if his sub does not trust him, she will be released?

It's individual of course and always based on a case by case basis but I don't think anyone can say that in a general statement - I get that no one wants to be mistrusted but if you have to be angered everytime at being questioned, I would see it as defensive your part and maybe there is a reason you feel threatened by the mistrust; like maybe it is well placed and you don't like it being pointed out?

Please don't feel like you need to answer all of the questions... this is just a few topics to get started with.

hehehe - It's a great topic lily