Choosing Commodus as his successor (obvious sarcasm)

Not an expert here, but a prior thread from u/TylerX5 touched on this subject. However, material was a bit sparse (mainly just an increase in persecution and some notes from Gibbon). https://www.reddit.com/r/AskHistorians/comments/1s7yxm/what_are_some_honest_criticisms_of_marcus/