What is this I don't even.

I sat on this without answering for a couple of days because I was trying to figure out how to respond. I know the answer, but I’ve regretted saying too much in offhand discussions before so I want to tread lightly with it. I’d like to think that the characters are/will eventually be explained well enough by the story itself, but then do I love jabbering on about what’s going on inside their heads, so… I think I’ll opt for being vague but mildly informative.

First, it all depends on what you mean when you say that they have “feelings” towards each other. They both feel things about each other, sure, but probably not the way one would initially assume from the phrasing.

Wheatley and Chell view each other completely differently. Each assigns a different meaning and a different significance to the other based on their past experiences, present situation, assumptions, perspective, goals, etc. So there is really no way to compare how much one feels about the other since they are mostly not the same feelings.

Though one feeling they have in common is that they prefer not being alone over being alone. Whether that is selfish of either is up to interpretation.

You have to view them in a certain frame of reference—they are (in a way) the first people they’ve ever met. Wheatley doesn’t know much about humans apart from the engineers he knew. Even Chell’s grasp of how to be around another person is shaky—yeah, she remembers some things, but there are gaps in her knowledge too. It’s just that neither she nor Wheatley recognize them, so they aren’t remarked on in the story. And for what she does remember, knowing things is not the same as understanding them. Or putting them into practice. (See: Chapter 13-15, and various other times when she’s done things that are probably not normal for people to do but neither of them would know it.)

So the whole topic is kind of complex for them. 

(And this was the short explanation!)

(Second question) Does Wheatley know that he has those scars on his spine? 

He’s not very observant. Well, he’s actually really observant, but that managed to pass under his radar. Besides, there’s much more interesting stuff walking around with him now.