User blog comment:Awayorafk/Believe. The Indoctrination Theory./@comment-96.51.21.52-20150101231853/@comment-173.186.128.90-20170615045424

My idea is that Harbinger leaved because he REALLY UNDERESTIMATED Shepard.

We've seen Reaper beams cut through buildings and destroy shuttles, and Garrus said it "kills nine or ten platoons with one single shot" (After Palaven battle). In fact in ME3 most Reaper beams fires at battle TEAMS VEHICLES, AND BUILDINGS, which guarantee multi-kill with one single shot. There are exceptions of Tuchanka and Rannoch, but in BOTH cases, SHepard was almost the ONLY target available, and was ACTIVELY posing SIGNIFICANT THREAT (Karos & Fleet bombardment) to those Reapers in question.

Also, it should be noted that In BOTH (again) cases, Reaper only attempted to shoot Shepard THEMSELVES when their minions are absent: in Tuchanka case, the Reaper ceased firing when tons of brutes and other minions arrived (although all the stomping happened afterwards is hardly anywhere better), and in Rannoch case, the Reaper just sit and watched until Shepard eliminated all Geth guards and fired on the Reaper ITSELF. Suffice to say, Reaper beams don't fire if there isn't a hell of the threat/kill.

So turn back to Earth case. Yes, there were Shepard and Harbinger, but Shepard is dying already, on last breaths, walks super slow, and only had a pistol. While on Harbinger side, there were at least three husks and Murander Shield, probably more. So I think Harbinger just concluded that "Yep, these should be enough to finish off that dying animal" and left to cut through ships, tanks, that sort of "more threatening things" which also have much higher "Expected kill counts"

AND HE UNDERESTIMATED SHEPARD'S POWER! BADLY!