How does this aspect manifest? My 1° Aries Mercury in 2nd house makes only two aspects -- square to 0° Cap Mars in 12th, and wide square to 22° Gemini Jupiter on cusp of 6th, forming a T square. I'm wondering if either of these would indicate a tendency to miss what in hindsight seems obvious, or to act out of habit without thinking. Or is it the Mars-Jupiter opposition? So many "Aha!" moments now when I look back at my early years.
I sympathize with how crazy making the 6th house can seem. I wonder about the orb ? Seems a bit wide
-6th house stellium
You would push your beliefs; and I mean "assert"; with no negative connotation. You would tend to think you are right... and may be prone to overconfidence.
I am in the same boat. 
On the, missing something in hindsight, I think this is the reason. You're confident and Mercury in Aries can be rash.