Beginning with the premise that I don't agree with everything that is now canon (I mean, I had different expectations for book 7 Snape, and I don't quite agree with the over-importance of Lily), I'd say that one of the most interesting aspects of Snape is exactly that his character is complex, still mysterious in many ways, and that surely fans stick with him also thanks to this possibility of interpreting his character in different nuances. I mean, re-interpretations and adaptations are the way characters survive in collective memory - think of Lancelot-as-hero // Lancelot as Arthur's rival // Lancelot as victim // etc, just to make a very lame example.

I don't know what's okay to think anymore

I'd agree, exactly because I believe that Snape is not a linear character in canon, that JKR had many unresolved issues in her way of describing him, and that not necessarily OotP Snape makes sense with HBP Snape or DH Snape. IMHO, at least.

I agree with him having a deep passionate heart, and with that being the reason why he tries so hard to hide it and to protect himself from being wounded again because of his sensitivity.

The parallel with Byronic features was very interesting, thank you.