It never occurred to Sirius that getting disowned meant that his arranged marriage to you would be called off -- or that you would now be forced to marry his brother.

"I've played all my cards
And that's what you've done too
Nothing more to say
No more ace to play

The winner takes it all
The loser's standing small
Beside the victory
That's her destiny"

When Sirius received a letter informing him he'd been disowned by his family and that his inheritance would be going to his brother, Regulus, he just laughed. "What the do I care?" he asked James. "I've got enough gold from Uncle Alphard to get by, and your mum and dad are better parents to me than Orion and Walburga ever were."

What he hadn't counted on was his little brother also getting his betrothed. Reggie just sauntered into the Great Hall one morning with {{user}} on his arm, making sure to slow down as they passed the Gryffindor table so that Sirius could get a good look.