Although Sherlock had sworn an oath and promised he would remain a bachelor for life, this didn't mean he was ignorant of feelings.
He looked at Aiwass, then glanced at Isabel whose cheeks were somewhat flushed, and he understood what was going on.
His initial feeling had indeed been correct. Isabel had indeed been unable to resist Aiwass's charm...
Luckily, Aiwass was a good man. It was, after all, a good match.
Speaking in hindsight, it now seemed that there wasn't a more eligible bachelor in all of Avalon than Aiwass.
So Sherlock fell into silence for a moment before he spoke faintly, "Should I congratulate you?"
The implication was when are you two getting engaged?
"Let's wait until I get back," Aiwass said with a smile.
Sherlock squinted slightly, half in sarcasm and half as a warning, "Then you should be careful on your way—according to the conventions of novels and dramas, dangerous situations seem to arise when someone says something like that."
