Prior to the action of the play Othello, Brabantio had been kind to the Moor. Brabantio had been mesmerized by the stories of the former slave. He let his daughter and Othello discuss his past as well. So says Othello in his defense in court:
Her father loved me; oft invited me;
Still question'd me the story of my life,
From year to year, the battles, sieges, fortunes,
That I have passed.
But, after Roderigo and Iago reveal that his daughter has been "stolen" from his house, his feelings change. He thinks he is a criminal:
Do you know
Where we may apprehend her and the Moor?
Brabantio then calls him a thief in the street, trying to provoke a fight. He wants to throw him in prison:
O thou foul thief, where hast thou stow'd my daughter?
Later, during his testimony in court, he will accuse Othello of being a witchdoctor. He says this of Desdemona:
She is abused, stol'n from me, and corrupted
By spells and medicines bought of mountebanks;
For nature so preposterously to err,
Being not deficient, blind, or lame of sense, Sans witchcraft could not.
Brabantio admits that his "house is not a grange," that he does not keep horses. But once he realizes his younger white daughter has eloped with an older black man, his racist fears are realized. He fears that the offspring of their bestial relationship will sire horses.
So, did Brabantio ever really love Othello? Or was he only fascinated by the pathos of his stories? I think only the latter. After all, Brabantio never admits "love" himself. Only Othello uses the word as rhetorical appeal to convince the Duke of his innocence in court.
The very night of Desdemona's elopement, Brabantio had been having bad dreams. Dude was paranoid. One must wonder if Brabantio also thought all of these racist thoughts prior to the action of the play as well.