Spike has always shown the love probably more than the other vampires and you are correct, probably it's the way he was as a human and those qualities transferred over when he was a vampire. When Spike was human, he really loved his mother and was even doing poetry and when he turned to a vampire, he still actually loved his mother and never wanted to hurt her... and he still had the love part.

Dru was a bit insane when she was human and became more insane as a vampire.

Darla was a prostitute but it's not much we knew about how she was as a person, we just knew she wanted to survive and she really didn't seem to have anyone by her side so most likely a rough past.

Angelus was a bit rebellious and hated his father... and that definitely transferred over when he was a vampire.


So, I actually would like that theory a bit more that parts of when you are human transfer to your vampire state although I don't like how the writers pick and choose how and when ti change thing especially when it comes to the soul and the soulless.

Harmony was the exact same as a vampire and human. Didn't take her seriously as a human or as a vampire... she was never a real threat...

When it comes to Angelus/Darla that's why the scene when she choose Angelus over the Master was just so powerful because Darla and the Master was really close and she was his favorite!