Question - does Barnabas actually know what "love" is?
The B Man did love members of his family: Naomi, Sarah & Jeremiah--up until Jeremiah eloped with Josette and Barnabas killed him for it, of course.
He obviously saw Josette as
the shining example of womanhood, for better or worse, and Angelique's unique brand of love surely warped his mind: the destruction of his family, having Josette ripped away from him, being cursed by his affliction...well, we all know that Barnabas has issues. And being chained up in that coffin for 170 years didn't do much for his mental health.
I think when Barnabas was freed from his tomb, he saw an opportunity to make the world that he wanted in 1795, and he didn't care how he did it. He was a victim of a psychotic, evil supernatural social climber; Angelique not only ruined his life--she ruined any chance he had of finding peace in death.
Maggie's resemblance to Josette drove him even more batty--no pun intended--than he already was; but, eventually, Barnabas learned that kidnapping a girl and jacking hard with her mind was no way to find true love. If Barnabas did indeed ever exhibit emotional growth, it was when he finally fell in love with Vicki for who she was, abandoning that dopey plan of re-creating Josette.
And while I dearly love Julia, she was as calulating and sociopathic as Barnabas was early on; she didn't care about helping Maggie, and while she was squeamish about putting the needle to Dr. Woodard, she did it anyway--because by that time she was truly Barnabas' co-conspirator, her own free will putting her in that horrible position.
If she really wanted to help Barnabas, she would've blown off the cure and helped put the horrors of the past behind him...