Otto Zwierlein is the author of two major monographs in German (see my bibliography) outlining his theory about when, and why, legends about Peter in Rome were invented. His thesis is that the traditions about Peter in Rome emerged as a response to the traditions from Justin Martyr onward that Simon Magus was in Rome, for the leading Apostle Peter had to defend Christian orthodoxy against the arch-heretic Simon near the origins of Christianity in Rome, but some of Zwierlein’s arguments include dating some texts later than conventional (e.g. the Ignatian Epistles) or reinterpreting some of the earlier data (e.g. “Babylon” in 1 Peter 5:13 or Peter’s suffering in 1 Clement 5:4). He describes the impetus for his research and its implications here and there are English reviews of his first monograph by Pieter W. van der Horst in the Bryn Mawr Classical Review and James Dunn in the Review of Biblical Literature. An edited volume in German was also written in rebuttal against Zwierlein’s views and you can read an English review of this response volume here.