User blog comment:Legionwrex/Sovereing is irrational/@comment-730941-20100920022424

Rationality is a matter of perception. Sovereign perhaps believes it is rational, and gives the player that impression, but never thinks to investigate its own origins - it doesn't realise this contradiction perhaps because of its own 'personality', so to speak.

Its irrationality extends to other areas as well, come to think of it. I'm sure a gigantic squid shape isn't the most efficient/powerful combat system possible (in terms of area of fire, surface area of shields), and purely rational beings (which the Reapers claim to be) wouldn't hold a grudge against Shepard precisely because they're meant to be rational. Harbinger specifically mentions that they're going after Shepard in particular, which makes no sense from a rational point of view - there are far more powerful threats in the galaxy (for example, the Citadel/Alliance fleets).