Now you want to have one of your own.

Oh! shocking, cousin,' said Mr.St.Clare, who loved to tease.
'Nonsense! I only want to have her, so that I can set her free.' 'Very well,' said Mr.St.Clare, 'I will write the paper for you.' Then he sat down and began to read.
'But I want it done now,' said Miss Ophelia.
'Why are you in such a hurry ?' 'Because now is the only time there ever is to do a thing in,' said Miss Ophelia.

'want to make sure of it.

You may die or lose all your money.
Then Topsy would be taken away and sold, in spite of anything I could say.' Mr.St.Clare hated being made to do things when he didn't want to.
However, after teasing his cousin a little more, he wrote out the paper, and Topsy belonged to Miss Ophelia.

That evening Mr.St.Clare went out for a ride.
Tom saw him go, and asked if he should come too.