This is book 2 of The Themis Files.

I enjoyed the first book enough to read the second book, and this was the second book. It starts about a decade after the last one ended, where everyone has pretty much become used to having a large (like 200' large), alien robot hanging out on the world doing book readings and press conferences.

And then another robot shows up and starts killing everyone.

The book moved at a more frenetic pace than the first one did, which is reasonable given the first one needed to world-build and this one can coast along on those words. Not everyone dies in the end, and we don't see enough of the characters we saw in the first one, and the rough edges have been smoothed off everyone's personality, all which contributed to this being a typical sophomoric book: less good than the first, but sufficient.

There's one more book in the series, coming out in May, which I'll read. I think this book is better experienced on audiobook, to be honest.

Military people — people like me — need intelligence to be useful. We need to know what’s going on. Without intelligence, take my word for it, you do not want your fate in the hands of the military. We do not improvise.
Page 18

Scientists are like children: They always want to know everything, they all ask too many questions, and they never follow orders to the letter.
Page 18

— Do you remember what you told me the second time around to get me to take this job?

— I do.

— You said: “I found you a military post where you’ll never have to kill anyone ever again.”

— I know. I still intend to keep that promise.
Page 21

People do what people do, and you’ll be miserable in the end because you’ll blame yourself for something you really have no power over.
Page 43

Every thought you have is a physical process. We know this for a fact, we can see it happening. We also know that emotions can be described in similar terms. Obviously, what you see, hear, touch, taste, smell is tied to your body.

...

Your soul, if you had one, the part of you that can’t be summed up as a bunch of atoms, would have no physical presence, couldn’t hear, smell, touch, or see anything. It would be incapable of thinking. No thoughts whatsoever, no sense of self. It wouldn’t feel anything either. Your soul would be… a hole… emptiness. There’s nothing special about that.
Page 46

I still find it impolite to give anyone lessons in their field of specialty.
Page 56

It’s not that I dislike the tame version of her — she’s doing it for me. I’d have to be a real asshole to blame her for it — but sometimes I wonder if she’s wiser or just broken. The thing is, she doesn’t seem unhappy. She says she’s happy, and a lot of the times I believe her.
Page 57

— Before Ms. Resnik became… Ms. Resnik, she was a little girl, with a mother of her own. No relationship is perfect, and I imagine that this little girl knew exactly what kind of person she wished her mother to be. Do not underestimate how powerful the wishes of that little girl are, to this day.
Page 58

"If I have, in any way, willingly or not, led you to believe I was remotely interested in your opinion of me, it was my mistake. It will not happen again."
Page 105

I started small and tried to make Themis move by a distance of one. I didn’t know one what, exactly, but I figured I’d probably end up somewhere on the empty lot in front of the hangar.
Page 109

I laughed at this. "One, in the appropriate unit."

"I still disagree with you. I think this is a bad way to die. It’s pointless. I just don’t have anything better to offer."
Page 124

While I am reasonably confident you are not “the chosen one,” you are without doubt one who has been chosen.
Page 125

We cheat and we lie at peacetime because we know the other side does it too. This might be war, and in war, you don’t try to scam your allies.
Page 129

The cost of an eradication effort is, generally speaking, inversely proportional to the population density.
Page 132

"Four million dead is indeed terribly sad."

"I don’t mean that. I mean it’s sad that their deaths aren’t as important just because there are so many."
Page 154

"And therein lies the fundamental difference between us. You would not sacrifice your principles for a greater good. I would not stop to think about it. I am… pragmatic, and you, Dr. Franklin, are an idealist."
Page 194

"Parents feel a great deal of responsibility for the way their children turn out, but there is very little a parent can do that will remotely rival the influence a friend or lover can have."
Page 199

I started out thinking I could remove the bad from the world one piece at a time until there was none left. The world, unfortunately, does not work that way.
Page 203

Remove a bad man from power, and a year later the person you put in his place is just as corrupt. If a policeman stops a drunken man from beating on his wife, what are the odds he will never have to go back? Can he really prevent anything, or is he just delaying the inevitable?
Page 203

Well, you’re not special, no more special than every other magnificent thing in the universe.
Page 233

Kara had the most beautiful smile when she was proud of herself. Smug, like you wouldn’t believe. Made you want to punch her in the face, but it was beautiful.
Page 244

I sure wish you were here with me. I’m better with you around. You know when I’m about to do something dumb. You put your hand on my shoulder to stop me from doing it, or you don’t and we do something even dumber together. Either way, I know everything’ll be OK. I’d give anything to have you with me now. See if you’d put that hand on my shoulder or not. I’d feel a whole lot better if you were here to help me plan this thing.
Page 259

Remember how unhappy I was awhile back? I didn’t even know I was, but I was. It was because I thought I had to be someone else.
Page 260

I’d never do anything if I waited for good ideas.
Page 266

Now I’m overanalyzing everything, wasting time thinking about wasting time.
Page 289