Just a couple plot questions... [spoilers]

[Razalhague]

Here's one that's a bit of a storyline conflict:

Spoiler below!

Why does Phillip feel bad about killing the (ex)Dr. Amabela? Obviously what Clarence said was a lie, because even if he were deceiving him, how would she come to perfectly stand underneath a weight threatening to crush her without suspecting a thing?
So either
a) She really was infected and he was not hallucinating (and therefore not his fault), but this makes little sense since her uninfected form re-appears. If Clarence were again causing this, Phillip would have to be pretty inept to think he actually killed a human, given (b).
b) She wasn't infected but was stupid enough to stand underneath a weight as she watched Phillip lower it (damn, that's trust)
c) Clarence has taken motor control of Phillip and forced him to kill her by his bare hands while at the same time portraying a different picture to Philip (which is sort of absurd and contrary to the story line that Clarence can only control perceptions).

Lucy, you got some s'plainin' to do.

I'll just copypaste from the steam forums what I wrote on this:

Spoiler below!

So, why did she do all that? It's rather simple, she really was infected.

The main thing here is that she can harm and kill you. Clarence doesn't want to kill you, later on he even helps you and warns you of danger a couple of times before you're ready to get rid of him. It doesn't make sense he'd kill Philip with a hallucination. Even if he wanted to, earlier we see what happens when hallucinations try to attack Philip: there's the greaking glass thing and nothing actually happens. No, the infected really was infected.

Then there's the fact that we never see Amabel during the video-chats. Add to that the fact that a person may sound quite normal and then a couple of seconds later turn out to be infected (as evidenced by the doctor who was going to "lend us a hand").

So, I think that Amabel had lied, and had in fact been infected. Instead of Clarence distorting Philip's perceptions before the killing (to make her seem infected), he distorted his perceptions after the killing, to make her seem uninfected. Why? I don't know exactly. If I had to say something, I'd say it was to make Philip feel guilty for killing her, so he wouldn't "kill" Clarence. Obviously didn't work like that, though.

Spoiler below!

It can't be b) because Clarence doesn't seem capable of causing actual harm to Philip, but the infected in question can. It can't be c), because even when Clarence's life is directly in danger, he can only disorient Philip.

When you have eliminated the impossible, whatever remains, however improbable, must be the truth.

Anger can make a person very irrational. I think it's quite believable that Philip didn't stop to think about the events in enough detail to realize how unlikely it would've been for the infected to really be Amabel.