Amanda Waller is one of the more distinctive presences in the DC Extended Universe. She occupies an unusual space, neither the stereotypical villain nor hero, possessing no powers whatsoever but making up for it entirely through intelligence, political reach, and an absolute willingness to do whatever she determines is necessary.

Her two most prominent appearances are in the Suicide Squad films, where she serves as the architect behind the group rather than a participant in any of the actual fighting. Whether or not her methods are defensible, it is worth noting that without her intervention, a demonic entity was on the verge of leveling everything in its path, and apparently no one thought to notify Superman, Wonder Woman, or Batman about any of it.

Her primary instruments were information, threats, and the credible fear that she would follow through on both. She knew exactly what leverage to apply to the right people at the right moment, and she held knowledge that extended all the way to the secret identity of Bruce Wayne. She does not appear to be driven by any particular political ideology or personal enrichment. What she serves is the institutional interest of the United States government, and in service of that she has no apparent ceiling on what she is willing to do, including blackmail and killing.

She becomes genuinely difficult to sympathize with in the second Suicide Squad film. When a classified government program begins causing mass civilian casualties in another country, her response is to order the team to stand down and report back, threatening to execute them remotely if they refuse. She is stopped only when one of her own staff knocks her unconscious before she can act on it.

That is essentially the full picture we have of Amanda Waller in the DCEU. James Gunn has generally been cautious about carrying roles over from the previous continuity into his new one, but if he chooses to bring Viola Davis back in this particular part, it would be hard to argue against the decision. She portrayed the role with such conviction and precision that any criticism of the casting would be difficult to take seriously.