A Timely Warning (джен)

Takes more from Norse Myths than the comics, but primarily based on the MCU. Starts one century before Thor's planned coronation, first in an ongoing series.
Time travel isn't impossible even if you don't have the Time Gem, but using it to change anything more than a few days past is widely considered the most effective way to go insane. So when Loki receives a package apparently from his future self he is understandably concerned. The Wheel of Time continues to turn, and whatever happens in this iteration of the universe, Loki will not ignore this herald of dangers to come.
Of course, that would require that he understood the message. Unfortunately, the package arrives when Loki is still a developing adolescent instead of in the week prior to Thor's coronation. [May, 1911 AD]