All things have their accomplishment in accordance with the nature of the Whole: it could not be in accordance with any other nature, either enclosing from without or enclosed within, or any external influence.
In the first passage, we learn that we can make our own judgments about whatever happens. Hadot adds this to Marcus' passage, "this does not mean that the guiding principle can imagine anything it pleases about reality, but rather that it is free to attribute what value it wishes to the objects it encounters. ... If we suppress the inner discourse which says "I have been harmed," then the harm disappears and is suppressed (IV, 7)."
The second passage is a bit cryptic, but I understand it to mean anything that happens is in accordance to nature. I read this in the vein of cause and effect. If something can happen (perhaps according to the laws of physics) then we should not be surprised when it does happen.
(see also Citadel p. 110)