"Oh sure, you just go right on being oblivious, and I'm just going to go find someone to obliviate me later." He said giving his brother a mock glare. "Can I help that they liked telling when we shagged?" He smirked, though there were plenty of rumors that were entirely untrue as well - not that he'd ever done anything to dispute them. "Of course I love you, you prat." Not in the way most people meant when they said that, but in the best way he knew how he loved Regulus.
Sirius grinned. "Of course you have to be nice to him." He smirked, glad at least that he'd somehow given Regulus a reason not to hate James, at least for the time being.
"Yes, yes you're completely amazing." He snorted when Regulus reminded him of their mother's portrait. "At least she'll be glad to have you home again." He teased. "I can only imagine how pleased she'll be to see me, I've heard stories about the last time she and I met." It amused him to no end hearing those stories from Harry.