[Enoch waits a bit, watching the thread with the other (non-human!) person branch off, hoping to learn something else. When it seems to have come to a stopping point, he replies again.]

I didn't know something as basic as our blood could be so complex! My options are so few, though. It's a shame I can't help more people. I suppose this is something that can't be changed?

[He's ancient, he doesn't know! But he can guess.

It could be worse, he could have had AB, which would be even more limiting...but that doesn't really help him feel less inadequate.]