have fun playing the game exactly the same way you played your first character. Of course, there could be some difference, mainly that you become stuck with very little to do but explore and shoot stuff(which will be like your side activity first playthrough).
Cuz, your only option is "No". "Will you help me" "No". But you will become stuck, because in order to progress the MQ you have to say "yes" and you have to "care".
Spoiler Will you save the Minutement: "No". Done.
Will you become the Silver Shroud: "No". Done.
Will you find the cure in V81? "No". Done.
Will you help Cait or McCready? "No." Done.
Will you help Settlers? "No". Done.
Will you help Bos? "No." Done.
Will you help RR? "No." Done.
Will you find Nick Valentine? "No." Game over, unless you say "Yes".