Does anyone remember the ending lines of the OWB expansion for new vegas? About how old world blues were people who were so caught up in the past that they couldn't see the present? For me, and I may be alone in this, that sums up the Institute and the Brotherhood. No one faction was totally evil in the way the Legion and Enclave were, but each were obsessed with their one goal to the point of ignoring everything else.
We have arrived, and it is now that we perform our charge.
In fealty of the God Emperor (our undying lord) and by the grace of the Golden Throne,
I declare Exterminatus on the Imperial world of Typhon Primaris.
I hereby sign the death warrant of an entire world, and consign a million souls to oblivion.
May Imperial justice account in all balance
The Emperor protects.
-- Task force of the Ordo Malleus, immediately before carrying out Exterminatus on Typhon Primaris.
Thought for the day: It is better to die for the Emperor than to live for yourself.