It makes me rather angry when someone dismisses relationships and feelings and experiences because they are "only" online or long distance. To continue the mountain climber/rock wall analogy, if the rock wall is challenging and satisfying to the person climbing it, and especially if it's all they have available, let them climb. Stop comparing and judging and looking down on people. Unless you're the best mountain climber in the world, there are people out there who can look down on you, too, if they so choose. If you're a part of an ONLINE community, guess what? You're in an online relationship, too.

One of the things that is so awesome about this particular site is that treating people with respect is a rule. So we all need to follow the rule. Respect others and -whatever- relationship they are in. You don't have to like it, agree with it, or choose it for yourself, but you do have to show respect.

Having expressed my opinion there, i believe the original post was asking what an online/long-distance submissive is responsible for in a scene or relationship with a Dominant. (OP, please correct me if i am mistaken that you are not asking in comparison to a real-life interaction, but are solely viewing the online aspect.)

My personal belief is that an OL/LD submissive first has the responsibility of his/her own safety. This may include any or all of the following: protection of (i'm going to use 'her' as the pronoun here) her personal identity; an understanding her of own limits and how to communicate them effectively; to make sure that a safeword is established prior to engaging in any play; understanding and communication of any physical or emotional issues that may be affected by play. Honest communication is absolutely key: a Dom/me who is not physically present has no nonverbal cues to depend on and cannot possibly be expected to read minds.

If there will be physical participation of any kind, a submissive has the responsibility to ensure her physical safety as well; basic knowledge of ropes, for example, as well as safety scissors to cut with in the case of an emergency.

i'm sure there are other things, but these are what most immediately came to mind.