That caption, like most, sprung directly from out of the dialogue in the scene:
JULIA:
...
Adam, you love him. You love him. Don't you realize that, Adam? Yes. He created you. Without him, you'd, you'd be dead. You do feel that, don't you, Adam?
...
Also, the opening voiceover tells us: "... And now in this old house, he is determined to end the life of the one person he has loved in his short life."
Adam did love Barnabas at first, which - if I remember correctly - was what made it so traumatic for Adam when Barnabas disciplined him so harshly.
Exactly! Which is one of the reasons I've always wondered how some fans can say they don't have sympathy for Adam even at the beginning of his storyline. But then, if, as some claim, they fast forward through his scenes even at that early stage, one supposes it could be very easy to miss such plot points. :-