Am i

Yeah, I was pretty surprised too

And that blush kinda came out of nowhere,like WHAT???

Exactly! It's so out of his character I'm not sure what how he truly feels about Alex. It made me think that maybe just maybe he developed some kind of feelings? But he didn't seem like the type to... :/

It's also kinda because they cut off the explicit scenes,so we don't see it in detail and that may have contribute to why it's a bit confusing, cuz he was always stoic in all previous chapters,in his characters or whether in bed, so it was totally out of character,it just came out of nowhere, which didn't make sense at all.

I guess from my point of view, Alex playing rough yet gentle at the same time, and it kinda make Clark caught of guard. And from what we've seen all this time, Clark have been dominant over Alex (sex, interview, etc). Yet, in chapter 42 very suddenly, Alex makes Clark submit to him. Its unusual but not that surprising since Alex have been holding his anger and frustation towards Clark. He is a killer afterall and in love with him.

And my guess he doesnt feel the same way towards Alex at all, he's only interested by his killing motives not the person itself. If he develop the same feelings, why he still keep looking at the doctor? For someone who's very much apathetic like Clark, maintaining relationship in such a long time to someone he does care is hard. He still care for him, and it shows bluntly.