Before meeting her in person, Philip Buchanon speaks with Amabel several times over a video chat - though while she can see his face, he cannot see hers. Through speaking with Amabel it's made explicit that Philip is infected:
I think one of the Inuit workers made it, but others were taken, some panicked and got lost. I ran - when I stopped, I was on my own. Oh, and another symptom is déjà vu.[...]
Watch out for signs of infection. [...] Look, the symptoms we know about are paranoia and aural distortion. Oh, and another symptom is déjà vu.
Philip is already experiencing some of these symptoms:
Philip hears her describe déjà vu twice - the same voice sample plays both times.
Clarence has already begun speaking to Philip by this time.
When Philip returns with the key card, he enters but does not find Amabel. After looking through her lab, he is attacked by a Tuurngait infected, which he dispatches by dropping a heavy weight onto its head.
Philip hears Amabel's shriek and discovers that Clarence utilized his ability to manipulate Philip's perceptions to fool him into seeing Amabel as an infected attacking him, thus tricking him into killing her. It's unknown what actions Amabel was truly taking - the Infected that Philip perceives blatantly attacks him (and can kill him), but walks after him much more slowly than previously encountered enemies. The intent to harm may have been also projected by Clarence.
Philip fortunately finds that, apparently foreseeing her possible death, Amabel had left notes on her PC instructing Philip in producing the necessary formula to cure himself of the infection, indirectly resulting in the "death" of Clarence and the beginning of Requiem.
Wow, you look like you've crawled through a sewer to get here - I suppose I'm flattered. Hi. I'm Amabel - Amabel Swanson and... I suppose I'll be your guide for the day.
Hello, can you hear me? I think the transmission's only one way... I've got webcam, pull a silly face if you can hear me. Oh, very attractive! OK, we're on. There's some things you need to know.
We released a virus. It wiped us out. Three weeks ago, we tried to get out through the mines but it didn't work the way we'd planned.
I think one of the Inuit workers made it, but others were taken, some panicked and got lost. I ran - when I stopped, I was on my own. Oh, and another symptom is déjà vu.
The only chance we have is a man called Howard. He said he'd found a solution to the virus. His vitals last registered in the library, but only members of... the organisation have access.
I'm still seeing a few life signs in the residential quarter... you need to find a survivor, and get through into the library. Oh, and look out for our medical guy, Richard Eminiss. He was acting... strangely, when I last saw him.
Hmm... what else don't you know? Let's see... watch out for signs of infection.
Did... did you say something? Look, the symptoms we know about are paranoia and aural distortion. Oh, and another symptom is déjà vu.
Well, I think that's everything you need to know. I'm sending over some research on the virus, and I'll get some doors open for you. Maybe now we can shoot the shi-
Christ, you look worse than last time I saw you... though maybe you're just at a higher resolution. Damnit! Note to self - never insult your last hope of survival.
I just wanted to give you a word of advice - those creepy artefacts - we don't know how they work. Or even what they do, I suppose. We... well, I... saw someone get too close to one, once.
You... probably don't want to know. I'm sure you'll be fine! Probably. I hope.
By the way... If you happen to find yourself in my neck of the woods, I'm kinda trapped. It's no big deal, really, just throwing it out there.
You came! I... guess I didn't really expect you to bother. My lab partner's such a pessimist - was such a pessimist, it kinda rubbed off on me.
He tried to make it through to me not too long ago - I guess he's a bit late for the party.
You'll have to make a quick detour over the surface next - but be careful, if the cold doesn't kill you... well... let's just say I didn't pick the safest of locales for my last ditch survival attempt.
OK, good news... good news... Oh yeah, I think I've got a cure! Well, it's not really what you'd call a cure cure, but it should be enough to help you.
I don't think I'm infected, I was careful, but... I guess if you come rescue me and I'm looking at you like you're a roast chicken, I got it wrong. Sorry - that probably wasn't funny, was it? No, I suppose not.
Well... hope to see you soon.
You know, you turning up here is probably the second best thing to happen to me since I've been down here. I'm reserving first place for when we get out.
So... I'm not big headed enough to think you came all the way here just to rescue me... I wasn't lying, I think I've worked out how to disinfect you, but - you probably saw this coming - it's not quite as simple as all that.
I had to engage the failsafe on the research rooms to seal myself in here - and that means we need a key card to get me out.
One of the personnel - one of the infected ones - tried to get in with a card, but I don't know where he, where 'it' went.
Look. I, I need you, and, well... if you do get me out, I'll give you the biggest hug of your life.
Her surname, Swanson, could be a play on the term swan song, as it was planned from the start that Philip was going to accidentally kill her.
A common fan theory is that Amabel really was infected, however Penumbra lead writer Tom Jubert refutes this.
Other evidence, such as the presence of a similar infected tissue as the one tossed out of Dr. Richard Eminiss's window just before he attacks Philip, can be excused by the fact she was obviously studying infected material to devise a cure.
Amabel Swanson shares her name with another character, Amabel Carlito, the Sous Chef of The Shelter. This was unintentional, and occurred due to writer Tom Jubert liking the name Amabel.
↑[...] The idea, of course, was to have the player murder his only ally in the game, as a result of the alien infection that’s rotting his brain. [...]
She’s the same person the moment she dies as she is when she meets the player, and that’s because she’s not really a character in the traditional sense – she’s more of a narrative tool. God, she’d hate me for saying that.
↑Incidentally, if you noticed there was another character called Amabel in the game – yes, I screwed up. I like the name, OK?!