Looking at Aberforth, it seemed pretty obvious to Horatio that his friend had avoided sleep for quite some time. "You know, I thought I was the insomniac out of the two of us." He commented as casually as he could before suggesting, "how about you get some rest? I'll take care of things in the meantime."
“And what, you’ve got a monopoly on that title?” Aberforth asked, running a hand over his face when he lifted his head to properly look at Horatio. “I’m fine. I can make it ’til close. It’s not like I have to travel to get home.” Sleep wasn’t coming easy for a multitude of reasons, but the most obvious was the recent encounter that he hadn’t mentioned to anybody. It had been four days, and he hadn’t slept for more than two hours at a time since. He rubbed at the spot on his arm without really thinking about it, and joked, “If you need a job, I could actually hire you instead of you trying to steal mine.”
“Doesn’t hurt to try, right?” Horatio replies, a grin flashing across his face before he turns more serious again. In all honesty, he was worried about his friend and he had the choice here: force the issue or drop it. Not an easy choice considering he didn’t want to drop it butt Aberforth wanted him to - yeah okay, the choice was easy. Of course he wouldn’t drop it.
“Are you sure? I don’t mind taking over so you can catch some sleep. You definitely look like you could use it, desperately. And just so you know, I’m not trying to steal your job, I definitely don’t want it... except if it makes you get some bloody rest.” Yeah he obviously wouldn’t drop the subject unless Aberforth gave him a pretty good reason (or several).